Use one vertex group. Add the objects of a costume to them. Here is two different weight values. But all must be at the same weights. Use a bone that is hardly being used and near the center of the costume, avoid the head neck arms and legs. Its very trickey and would work better as a script to run on a costume then to manipulate the objects. Its very easy to get it wrong and theres no way to correct it. You have to get it right with one try. DCMF may make a script after more testing. As you can see the angel's movements work very well.