We have one hTBH and this year our colony swarmed four times. We found homes for the first three but on good advice hived the last small swarm in the opposite end of the hive. Both colonies are thriving and the newcomers have built eight combs (only half the width of the top bar admittedly) in six weeks, all contain brood and honey stores. The ones in the original (West) end of the hive have 17 combs and plenty of honey stores.
They are separated by two ‘back to back’ follower boards, but one of them is not particularly bee tight as there is a window recess which we have not been totally successful in blocking; the other board is bee tight and the two colonies do not mix.
Is it possible to remove the follower boards and let them mix for the winter? If so, when should we do it? This way there would be plenty of stored food to feed both colonies, and the queens are both products of the same original queen. I have read (Christy Hemenway “The Thinking Beekeeper…”) that it is probably not uncommon for TBHs to house more than one queen. Any views would be welcome!