If I change a character head mesh using multi-part mesh, will there be a seam?

I’m building a character customization system with multiple head meshes. I’d like for the player to be able to choose one, and attach it to the body mesh. The character mesh so far is a single skinned mesh. If I chop off the head and make several meshes, then swap them around using multi-part mesh, will that create a seam at the neck? Is there a way to stitch the meshes together to prevent this? Should I use a different approach entirely?

I want to stay away from morph targets due to potential performance issues. I’m going to have many of these characters on the screen at once.