Yeah well, as long as they stick around, that's the main thing. If you didn't want to weaken a colony, you could borrow a frame of brood from it until you are sure the swarm is settled, then pay it back:)
Once the swarm is settled & the queen is laying, you could use one of those brood frames for swarms down the track. There are so many options we can use.
Another thing I was thinking was: Some of those frames from the cutout might not be A1 brood frames for the long term. They would be ideal for swarm captures.
It's worth remembering that not all swarms can be shaken, that's when a frame of brood comes in handy in catching the swarm.