Splitting organic mesh without visible seams

Hi, all!

I create character for game engine, but I need to split it into separate parts so it would be possible to replace parts and overcome some engine technical limitations (bones per mesh). So I need to split dense mesh parts (feet, hands, head) out to separate meshes.

If I just split mesh, everything works, but I see visual seams where meshes concatenate.

Experimentation shows the seams are due to how normals are calculated, as it does not have enough geometry on edge to smooth properly.

Is there some solution to this problem? Could I somehow transfer whole object normals on splitted ones?

Or maybe there is shader-based solution?

Also is there some way of non-destructive workflow for meshes which are split this way? So if whole mesh changed, split ones change too?

Thanks!