Reverse objects order in group I am trying to reverse the order of the object listed in a group using Python Console.
I do the following:
 1. Create a group from few selected objects as normal in Blender.
 2. In python console I create a list from the objects in the group.
 3. I reverse the list
 4. Create new group and add the objects from the reversed list.
When testing the group in the console the objects seem to be added in reverse order as expected. But after I save the file and reopen it the order of the objects in the "reversed" group was reset to the order of the original group.

So my question is - Is it possible to have two groups with the same objects but arranged differently in both groups?
ID property sortkey

Test script to demonstrate adding an ID prop as a sort key.  Creates two groups from scene objects "Group1", the second,  "Group2", in reverse order and adds a sort key  add_key(group)  

Saving and reopening the file and group.orderred_list returns "Group2" still in reverse order, as created.

import bpy
context = bpy.context  # for testing

def add_key(group):
    # simple integer key
    key = 0
    # add an IDProp key for each group object
    for o in group.objects:
        o[group.name] = key
        key += 8

    return None


def sorted_group(group):
    def key(obj):
        # key is groupname prop if set else 0
        return obj.get(group.name, 0)

    g = [o for o in group.objects]
    g.sort(key=key)
    return g

bpy.types.Group.orderred_group = property(sorted_group)


# test calls
scene = context.scene

obs = [o for o in scene.objects]


for name in ["Group1", "Group2"]:
    print(name)
    group = bpy.data.groups.get(name)
    if not group:
        group = bpy.data.groups.new(name)
        if name == "Group2":
            obs.reverse()
        for o in obs:
            group.objects.link(o)
        add_key(group)
    elif name == "Group2":
        sl = group.orderred_group
        # reorder by unlink link
        for o in sl:
            group.objects.unlink(o)
            group.objects.link(o)

    print(group.objects.keys())