Could you explain more in depth of what you want to do? I'm not sure I understand, do you want to alter two models and merge them somehow? If this is the case (or something similar) you can still save the texture, but you will have to reskin the models seperately youself. Basically you will need to use a skin editor like in MED to convert the 3D mesh into a 2D picture where you take the old texture and reapply it to the right spots.