diff --git a/yocto-poky/meta/classes/useradd-staticids.bbclass b/yocto-poky/meta/classes/useradd-staticids.bbclass
index 924d6ea..a9b506d 100644
--- a/yocto-poky/meta/classes/useradd-staticids.bbclass
+++ b/yocto-poky/meta/classes/useradd-staticids.bbclass
@@ -22,6 +22,30 @@
         and return it as a list"""
         return list(itertools.islice(itertools.chain(iterable, itertools.repeat(obj)), length))
 
+    def merge_files(file_list, exp_fields):
+        """Read each passwd/group file in file_list, split each line and create
+        a dictionary with the user/group names as keys and the split lines as
+        values. If the user/group name already exists in the dictionary, then
+        update any fields in the list with the values from the new list (if they
+        are set)."""
+        id_table = dict()
+        for conf in file_list.split():
+            if os.path.exists(conf):
+                f = open(conf, "r")
+                for line in f:
+                    if line.startswith('#'):
+                        continue
+                    # Make sure there always are at least exp_fields elements in
+                    # the field list. This allows for leaving out trailing
+                    # colons in the files.
+                    fields = list_extend(line.rstrip().split(":"), exp_fields)
+                    if fields[0] not in id_table:
+                        id_table[fields[0]] = fields
+                    else:
+                        id_table[fields[0]] = list(itertools.imap(lambda x, y: x or y, fields, id_table[fields[0]]))
+
+        return id_table
+
     # We parse and rewrite the useradd components
     def rewrite_useradd(params):
         # The following comes from --help on useradd from shadow
@@ -37,21 +61,21 @@
         parser.add_argument("-k", "--skel", metavar="SKEL_DIR", help="use this alternative skeleton directory")
         parser.add_argument("-K", "--key", metavar="KEY=VALUE", help="override /etc/login.defs defaults")
         parser.add_argument("-l", "--no-log-init", help="do not add the user to the lastlog and faillog databases", action="store_true")
-        parser.add_argument("-m", "--create-home", help="create the user's home directory", action="store_true")
-        parser.add_argument("-M", "--no-create-home", help="do not create the user's home directory", action="store_true")
-        parser.add_argument("-N", "--no-user-group", help="do not create a group with the same name as the user", action="store_true")
+        parser.add_argument("-m", "--create-home", help="create the user's home directory", action="store_const", const=True)
+        parser.add_argument("-M", "--no-create-home", dest="create_home", help="do not create the user's home directory", action="store_const", const=False)
+        parser.add_argument("-N", "--no-user-group", dest="user_group", help="do not create a group with the same name as the user", action="store_const", const=False)
         parser.add_argument("-o", "--non-unique", help="allow to create users with duplicate (non-unique UID)", action="store_true")
         parser.add_argument("-p", "--password", metavar="PASSWORD", help="encrypted password of the new account")
         parser.add_argument("-R", "--root", metavar="CHROOT_DIR", help="directory to chroot into")
         parser.add_argument("-r", "--system", help="create a system account", action="store_true")
         parser.add_argument("-s", "--shell", metavar="SHELL", help="login shell of the new account")
         parser.add_argument("-u", "--uid", metavar="UID", help="user ID of the new account")
-        parser.add_argument("-U", "--user-group", help="create a group with the same name as the user", action="store_true")
+        parser.add_argument("-U", "--user-group", help="create a group with the same name as the user", action="store_const", const=True)
         parser.add_argument("LOGIN", help="Login name of the new user")
 
         # Return a list of configuration files based on either the default
         # files/passwd or the contents of USERADD_UID_TABLES
-        # paths are resulved via BBPATH
+        # paths are resolved via BBPATH
         def get_passwd_list(d):
             str = ""
             bbpath = d.getVar('BBPATH', True)
@@ -63,6 +87,7 @@
             return str
 
         newparams = []
+        users = None
         for param in re.split('''[ \t]*;[ \t]*(?=(?:[^'"]|'[^']*'|"[^"]*")*$)''', params):
             param = param.strip()
             if not param:
@@ -72,10 +97,9 @@
             except:
                 raise bb.build.FuncFailed("%s: Unable to parse arguments for USERADD_PARAM_%s: '%s'" % (d.getVar('PN', True), pkg, param))
 
-            # files/passwd or the contents of USERADD_UID_TABLES
+            # Read all passwd files specified in USERADD_UID_TABLES or files/passwd
             # Use the standard passwd layout:
             #  username:password:user_id:group_id:comment:home_directory:login_shell
-            # (we want to process in reverse order, as 'last found' in the list wins)
             #
             # If a field is left blank, the original value will be used.  The 'username'
             # field is required.
@@ -84,65 +108,57 @@
             # in the useradd command may introduce a security hole.  It's assumed that
             # all new users get the default ('*' which prevents login) until the user is
             # specifically configured by the system admin.
-            for conf in get_passwd_list(d).split()[::-1]:
-                if os.path.exists(conf):
-                    f = open(conf, "r")
-                    for line in f:
-                        if line.startswith('#'):
-                            continue
-                        # Make sure there always are at least seven elements in
-                        # the field list. This allows for leaving out trailing
-                        # colons in the passwd file.
-                        field = list_extend(line.rstrip().split(":"), 7)
-                        if field[0] == uaargs.LOGIN:
-                            if uaargs.uid and field[2] and (uaargs.uid != field[2]):
-                                bb.warn("%s: Changing username %s's uid from (%s) to (%s), verify configuration files!" % (d.getVar('PN', True), uaargs.LOGIN, uaargs.uid, field[2]))
-                            uaargs.uid = [field[2], uaargs.uid][not field[2]]
+            if not users:
+                users = merge_files(get_passwd_list(d), 7)
 
-                            # Determine the possible groupname
-                            # Unless the group name (or gid) is specified, we assume that the LOGIN is the groupname
-                            #
-                            # By default the system has creation of the matching groups enabled
-                            # So if the implicit username-group creation is on, then the implicit groupname (LOGIN)
-                            # is used, and we disable the user_group option.
-                            #
-                            uaargs.groupname = [uaargs.gid, uaargs.LOGIN][not uaargs.gid or uaargs.user_group]
-                            uaargs.groupid = [uaargs.gid, uaargs.groupname][not uaargs.gid]
-                            uaargs.groupid = [field[3], uaargs.groupid][not field[3]]
+            if uaargs.LOGIN not in users:
+                continue
 
-                            if not uaargs.gid or uaargs.gid != uaargs.groupid:
-                                if (uaargs.groupid and uaargs.groupid.isdigit()) and (uaargs.groupname and uaargs.groupname.isdigit()) and (uaargs.groupid != uaargs.groupname):
-                                    # We want to add a group, but we don't know it's name... so we can't add the group...
-                                    # We have to assume the group has previously been added or we'll fail on the adduser...
-                                    # Note: specifying the actual gid is very rare in OE, usually the group name is specified.
-                                    bb.warn("%s: Changing gid for login %s from (%s) to (%s), verify configuration files!" % (d.getVar('PN', True), uaargs.LOGIN, uaargs.groupname, uaargs.gid))
-                                elif (uaargs.groupid and not uaargs.groupid.isdigit()) and uaargs.groupid == uaargs.groupname:
-                                    # We don't have a number, so we have to add a name
-                                    bb.debug(1, "Adding group %s!" % (uaargs.groupname))
-                                    uaargs.gid = uaargs.groupid
-                                    uaargs.user_group = False
-                                    groupadd = d.getVar("GROUPADD_PARAM_%s" % pkg, True)
-                                    newgroup = "%s %s" % (['', ' --system'][uaargs.system], uaargs.groupname)
-                                    if groupadd:
-                                        d.setVar("GROUPADD_PARAM_%s" % pkg, "%s ; %s" % (groupadd, newgroup))
-                                    else:
-                                        d.setVar("GROUPADD_PARAM_%s" % pkg, newgroup)
-                                elif uaargs.groupname and (uaargs.groupid and uaargs.groupid.isdigit()):
-                                    # We have a group name and a group number to assign it to
-                                    bb.debug(1, "Adding group %s  gid (%s)!" % (uaargs.groupname, uaargs.groupid))
-                                    uaargs.gid = uaargs.groupid
-                                    uaargs.user_group = False
-                                    groupadd = d.getVar("GROUPADD_PARAM_%s" % pkg, True)
-                                    newgroup = "-g %s %s" % (uaargs.gid, uaargs.groupname)
-                                    if groupadd:
-                                        d.setVar("GROUPADD_PARAM_%s" % pkg, "%s ; %s" % (groupadd, newgroup))
-                                    else:
-                                        d.setVar("GROUPADD_PARAM_%s" % pkg, newgroup)
+            field = users[uaargs.LOGIN]
 
-                            uaargs.comment = ["'%s'" % field[4], uaargs.comment][not field[4]]
-                            uaargs.home_dir = [field[5], uaargs.home_dir][not field[5]]
-                            uaargs.shell = [field[6], uaargs.shell][not field[6]]
-                            break
+            if uaargs.uid and field[2] and (uaargs.uid != field[2]):
+                bb.warn("%s: Changing username %s's uid from (%s) to (%s), verify configuration files!" % (d.getVar('PN', True), uaargs.LOGIN, uaargs.uid, field[2]))
+            uaargs.uid = field[2] or uaargs.uid
+
+            # Determine the possible groupname
+            # Unless the group name (or gid) is specified, we assume that the LOGIN is the groupname
+            #
+            # By default the system has creation of the matching groups enabled
+            # So if the implicit username-group creation is on, then the implicit groupname (LOGIN)
+            # is used, and we disable the user_group option.
+            #
+            user_group = uaargs.user_group is None or uaargs.user_group is True
+            uaargs.groupname = uaargs.LOGIN if user_group else uaargs.gid
+            uaargs.groupid = field[3] or uaargs.gid or uaargs.groupname
+
+            if uaargs.groupid and uaargs.gid != uaargs.groupid:
+                newgroup = None
+                if not uaargs.groupid.isdigit():
+                    # We don't have a group number, so we have to add a name
+                    bb.debug(1, "Adding group %s!" % uaargs.groupid)
+                    newgroup = "%s %s" % (' --system' if uaargs.system else '', uaargs.groupid)
+                elif uaargs.groupname and not uaargs.groupname.isdigit():
+                    # We have a group name and a group number to assign it to
+                    bb.debug(1, "Adding group %s (gid %s)!" % (uaargs.groupname, uaargs.groupid))
+                    newgroup = "-g %s %s" % (uaargs.groupid, uaargs.groupname)
+                else:
+                    # We want to add a group, but we don't know it's name... so we can't add the group...
+                    # We have to assume the group has previously been added or we'll fail on the adduser...
+                    # Note: specifying the actual gid is very rare in OE, usually the group name is specified.
+                    bb.warn("%s: Changing gid for login %s to %s, verify configuration files!" % (d.getVar('PN', True), uaargs.LOGIN, uaargs.groupid))
+
+                uaargs.gid = uaargs.groupid
+                uaargs.user_group = None
+                if newgroup:
+                    groupadd = d.getVar("GROUPADD_PARAM_%s" % pkg, True)
+                    if groupadd:
+                        d.setVar("GROUPADD_PARAM_%s" % pkg, "%s; %s" % (groupadd, newgroup))
+                    else:
+                        d.setVar("GROUPADD_PARAM_%s" % pkg, newgroup)
+
+            uaargs.comment = "'%s'" % field[4] if field[4] else uaargs.comment
+            uaargs.home_dir = field[5] or uaargs.home_dir
+            uaargs.shell = field[6] or uaargs.shell
 
             # Should be an error if a specific option is set...
             if d.getVar('USERADD_ERROR_DYNAMIC', True) == '1' and not ((uaargs.uid and uaargs.uid.isdigit()) and uaargs.gid):
@@ -161,21 +177,21 @@
             newparam += ['', ' --skel %s' % uaargs.skel][uaargs.skel != None]
             newparam += ['', ' --key %s' % uaargs.key][uaargs.key != None]
             newparam += ['', ' --no-log-init'][uaargs.no_log_init]
-            newparam += ['', ' --create-home'][uaargs.create_home]
-            newparam += ['', ' --no-create-home'][uaargs.no_create_home]
-            newparam += ['', ' --no-user-group'][uaargs.no_user_group]
+            newparam += ['', ' --create-home'][uaargs.create_home is True]
+            newparam += ['', ' --no-create-home'][uaargs.create_home is False]
+            newparam += ['', ' --no-user-group'][uaargs.user_group is False]
             newparam += ['', ' --non-unique'][uaargs.non_unique]
             newparam += ['', ' --password %s' % uaargs.password][uaargs.password != None]
             newparam += ['', ' --root %s' % uaargs.root][uaargs.root != None]
             newparam += ['', ' --system'][uaargs.system]
             newparam += ['', ' --shell %s' % uaargs.shell][uaargs.shell != None]
             newparam += ['', ' --uid %s' % uaargs.uid][uaargs.uid != None]
-            newparam += ['', ' --user-group'][uaargs.user_group]
+            newparam += ['', ' --user-group'][uaargs.user_group is True]
             newparam += ' %s' % uaargs.LOGIN
 
             newparams.append(newparam)
 
-        return " ;".join(newparams).strip()
+        return ";".join(newparams).strip()
 
     # We parse and rewrite the groupadd components
     def rewrite_groupadd(params):
@@ -192,7 +208,7 @@
 
         # Return a list of configuration files based on either the default
         # files/group or the contents of USERADD_GID_TABLES
-        # paths are resulved via BBPATH
+        # paths are resolved via BBPATH
         def get_group_list(d):
             str = ""
             bbpath = d.getVar('BBPATH', True)
@@ -204,6 +220,7 @@
             return str
 
         newparams = []
+        groups = None
         for param in re.split('''[ \t]*;[ \t]*(?=(?:[^'"]|'[^']*'|"[^"]*")*$)''', params):
             param = param.strip()
             if not param:
@@ -214,7 +231,7 @@
             except:
                 raise bb.build.FuncFailed("%s: Unable to parse arguments for GROUPADD_PARAM_%s: '%s'" % (d.getVar('PN', True), pkg, param))
 
-            # Need to iterate over layers and open the right file(s)
+            # Read all group files specified in USERADD_GID_TABLES or files/group
             # Use the standard group layout:
             #  groupname:password:group_id:group_members
             #
@@ -223,21 +240,18 @@
             #
             # Note: similar to the passwd file, the 'password' filed is ignored
             # Note: group_members is ignored, group members must be configured with the GROUPMEMS_PARAM
-            for conf in get_group_list(d).split()[::-1]:
-                if os.path.exists(conf):
-                    f = open(conf, "r")
-                    for line in f:
-                        if line.startswith('#'):
-                            continue
-                        # Make sure there always are at least four elements in
-                        # the field list. This allows for leaving out trailing
-                        # colons in the group file.
-                        field = list_extend(line.rstrip().split(":"), 4)
-                        if field[0] == gaargs.GROUP and field[2]:
-                            if gaargs.gid and (gaargs.gid != field[2]):
-                                bb.warn("%s: Changing groupname %s's gid from (%s) to (%s), verify configuration files!" % (d.getVar('PN', True), gaargs.GROUP, gaargs.gid, field[2]))
-                            gaargs.gid = field[2]
-                            break
+            if not groups:
+                groups = merge_files(get_group_list(d), 4)
+
+            if gaargs.GROUP not in groups:
+                continue
+
+            field = groups[gaargs.GROUP]
+
+            if field[2]:
+                if gaargs.gid and (gaargs.gid != field[2]):
+                    bb.warn("%s: Changing groupname %s's gid from (%s) to (%s), verify configuration files!" % (d.getVar('PN', True), gaargs.GROUP, gaargs.gid, field[2]))
+                gaargs.gid = field[2]
 
             if d.getVar('USERADD_ERROR_DYNAMIC', True) == '1' and not (gaargs.gid and gaargs.gid.isdigit()):
                 #bb.error("Skipping recipe %s, package %s which adds groupname %s does not have a static gid defined." % (d.getVar('PN', True),  pkg, gaargs.GROUP))
@@ -255,7 +269,7 @@
 
             newparams.append(newparam)
 
-        return " ;".join(newparams).strip()
+        return ";".join(newparams).strip()
 
     # Load and process the users and groups, rewriting the adduser/addgroup params
     useradd_packages = d.getVar('USERADD_PACKAGES', True)