Hi Steve. I’ve just posted a picture on a different thread. Transfer of nuc to hive
I used a board big enough to cover the space needed and cut a hole to accommodate both openings. So you could use a board to fit the Lang hive, put a nice big rectangle in it and cut most of the bottom of the polystyrene box off.
Having said that, you don’t want to merge a swarm with your existing hive if they both have queens.