No Matt, don't use the "Merge" button on each object. You'll lose all the groups if you do that. Save the OBJ to a new file name. Doesn't Mason's tutorial require you to rename the groups in the jeans first though? In that case you would import the Jeans.obj first, rename the groups, then bring the P4 male OBJ in on top of that with "Merge With Current File". I have a feeling you should check out the Jeans OBJ in Poser first because most of the clothing items have extra bodyparts that need to be removed. -JH.