not sure about blender but in maya you can use a blendshape to match vertex by ID for problems like changing proportions of a model to make variations. what sounds a little odd about what you've described is that you make a high poly for the proportion changes and then want to conform a game res model to that? Seems much…
I'm making game models for a hobby project. Some of these models is hard-surface armor. I'm making some of these armors different proportions to fit different sizes. The problem is, even with blender's shrinkwrap modifier the hard-edge outlines of the lowpoly will "slip off" the highpoly and they have to be meticulously…
in maya a blendshape just copies transform for each vertex ID, i dont think there is more to it than that recently there was a thread about retopology tools, and one i think called Wrap IIRC is shown, that conforms an existing base mesh to another model and you can designate matching vertices manually. Might check for that…