i've used the grouping tool to take parts from one prop and attached it to another exported it as obj and reimported it which made it into one prop.these were machine type props that had mostly square parts.info on how to do this is all in the user guide.i don't think this will work for clothing unless the polygons line up exactly.you could use the grouping tool to,lets say take the sleeves from one shirt and the body of another and take these into a modeling prog and create a single model.then you'd have to make it conformable.