If you thought you caught a feral swarm would you keep it away from other hives so it would keep the same genetics? any ideas?
Well, it will keep the same genetics so long as it has the same queen. If you mean to keep the genetics through queen supercedure, the question becomes how you will make sure she gets mated to a feral drone.
Unless you have a place where you can sequester away feral queens and feral drones and guarantee that no other bees are in the area, you might as well just put them with your other hives.
The trick is to just keep adding more feral hives and eventually their genetics will overwhelm whatever you currently have (assuming your goal is feral genes).