Arch: Fixed 'object in more than one group' bug in Arch

src/Mod/Arch/ArchCommands.py

@@ -126,11 +126,8 @@ def addComponents(objectsList,host):
                 a.append(o)
         host.Objects = a
     elif host.isDerivedFrom("App::DocumentObjectGroup"):
-        c = host.Group
         for o in objectsList:
-            if not o in c:
-                c.append(o)
-        host.Group = c
+            host.addObject(o)
 
 def removeComponents(objectsList,host=None):
     '''removeComponents(objectsList,[hostObject]): removes the given component or