give them a frame full of pollen and let them eat syrup. shut them down to 3 frames. you'd be surprised what you can get through the winter. i'd want to see what that swarm queen had to offer
That is the worst you can do.
Before winter, join hives, do not split.
In spring, join hives, do not split. Big colony build up much more better than 2 weak colonies.
In USA you get all the time new queens if needed. Or you buy a package and the big colony will be splended.
.When colony is 4 boxes big, then you may make nucs from it.