I never take my traps up. Leave them out year around. All mine are on plastic tubs about 2 1/2 feet high. If a late swarm goes in, and I don't find it, the bees have as good a chance of making it there as somewhere else. And, after all they choose where they want to stay.
I have caught swarms as late as 6 October, and by giving the a few frames of honey, they make it through the Winter.
Only problem with combining is, you add bees to colonies that are already weak and short on stores. The swarm likely has a better chance of making it than a weak colony that has been weakened by varroa, failing queen, poison, etc.
cchoganjr