I have to admit I've never tried making conforming clothes because the modeling software I mostly use (Rhino) is bad at doing the critical thing which is splitting the mesh into parts. In other words, in the case of an item that spans the hip-abdomen divide, you have to split it where the divide is going to be.

Then you combine the two bits in Poser in the correct hierarchy and save the combined obj file.

Then you cheat. You find another conforming cr2 file that has a similar structure of parts. Edit it to replace the name of the original obj file with the name of your new one, in two places, rename the file, save, it should all work.