Sorry, but I don't think it's a good idea. You can already do that with partial regeneration, just need to think differently (regenerate what you don't like instead of keeping what you like).
Adding a new way to do something that you can already do with the program would not add any extra value, it could be potentially confusing for other users, and it would require extra development resources that could be employed in GUI redesign / simplification or bug fixing.


Latest BIAB version, latest build.