I have not had trouble with the several hybrid figures I've made. 1. I don't position the individual parts before exporting thogh, I align the new configuration only with scale and translation to the figure "body" not the individual parts I'm actually transplanting. 2. Then I think I export with only the first box in the export dialog checked. Maybe these two things are what has lead to sucess for me, prior to this procedure I had the parts flying apart when I applied the morph dials. Furthermore, when atempting to merge props into an object I would import the prop and position it where I wanted, then export the prop and re-import it and then export it with the figure I was merging it to, this seemed to somehow "clear" the origin of the perop, yet I still had the prop flying off if I tried applying morphs to it. Only the procedure abaove has lead to stable merged figures for me.