gs branch split prompt which commits (upper or lower) retain the existing branch

[perspectivezoom]

Assume I have a stack master => featureOne => featureTwo => featureThree

• If I would like to split up featureTwo into featurePreTwo => featureTwo, gs branch split works great. The command assumes that the topmost set of commits (furthest away from master) will keep the original branch name.
• If I would like to split up featureTwo into featureTwo => featurePostTwo, I'm in trouble. There is no (easy) way to tell gs branch split that the bottommost set of commits retain the original branch metadata, and to create a new branch from the topmost set of commits.

I have to resort to naming the bottom branch temp, and then use gs branch rename to get my desired stack, but then I also have to gs branch untrack && gs branch track both branches to bust the existing PR references so things are in a good state.