The cr2 just tells poser what to do with the obj's parts and materials. If the umbrella only has one group and there are some poly's assigned to an (unknown group within the obj.) that isn't in the cr2 at all, those polys might be invisible. Some figures have many groups or parts and a group can have more than one material. If you have a material that isn't part of one of these groups then poser doesn't display it if I'm correct. It can still be in the obj itself still. Just attach the trim poly's to a known group that already exists in the cr2 with the group editor in Poser's setup room. Then resave the model. You'll know there's a poly that isn't assigned to a group when you leave the setup room because Poser will warn you as you leave and ask if your sure that's what you want to do.