The way morphs work in Poser, there need to be the same patterns of points in the object and in the morph. 100 lines of vertex data in the object, and 100 lines of data in the morph. (It's slightly more subtle than that, but they have to match.) You seem to be trying to find a way of working around that, and what you describe seems to be a 3d Max problem, which not many people here will be able to help with. But one answer might be to modify the .cr2 file so that it reads the head mesh from M3, and the rest from M3RR. It's possible, but it might not be as easy as it sounds.