This question is based on this one: What happens when the UA Bait and Switch maneuver is used on a grappled ally when the maneuver-user is out of the grappling monster's reach?
When you’re within 5 feet of an ally on your turn, you can expend one superiority die and switch places with that ally, provided you spend at least 5 feet of movement. This movement doesn’t provoke opportunity attacks [...]
What happens when the Bait and Switch maneuver is used on a grappled ally when both the maneuver-user and the ally are still within grapple range of the grappling creature?
I see two possible outcomes:
The maneuver-user takes the ally's place in being grappled, and can then attempt to break out of that grapple.
The ally is still grappled, but has now been possibly moved to a more beneficial position.
I am not sure which of these would happen, as normally in a grapple the grappled creature cannot ever move. (And I might be confusing myself by trying to think of how this would even work IRL.)