Well, remember if they are in the same folder, put PMG1's folder in first, put the PMG2's parts of that folder in then go to the next folder. Also, rename PMG2's parts to work. Example, you have a part in the head folder from PMG1 with the value of part 0. Lets say that's a goggle cap's hat. Likewise a goggle cap's goggles would be part 1. If you then import bunny ears and don't rename the parts, it would also be part 0. The bunny part would overlook the hat part causing it to look like just goggles and ears in the game. What you need to do is rename the bunny part to part 2, etc.
Also, there's generally only one order to import parts, at least from what I've seen.