I had a quick look into hives B, C and D yesterday afternoon. The news is mixed.
The best news is that I see no evidence of AFB. I'm not experienced enough to be certain so I'll continue to keep a lookout. I'll also review the NBU Foulbrood Diseases advisory leaflet.
Hive C is going very well. They're building in the super, rather than the deep box. They've almost filled the frames with comb. There are lots of brood. I saw sealed brood alongside recently hatched cells. The uneven pattern of hatching suggests that I need watch, to ensure it isn't an early symptom of AFB. The hive has plenty of stores. I saw the Queen, who is unmarked.
Hive D is definitely smaller. It has good stores and has built comb. I saw no evidence of laying: no eggs, larvae or capped brood. I didn't see the Queen (although that's not decisive). I'm fairly confident that they don't have a laying Queen.
Hive B has been there for only 6 days. I didn't see a Queen but it's too early to say what their condition is.
I'm thinking about the next steps. Hive C is fine and just needs monitoring. I need to confirm that Hive D is Queenless. If so then I have options: combine them with Hive C; buy a Queen or give them a frame of brood from Hive C in the hope that they'll grow up a Queen.
My preference is to add freshly laid brood into their Hive and let them create their own Queen. They come from the same mother colony so I'm less concerned about disease. They'll get a slower start to the year but that's ok. I now need to find freshly laid eggs in Hive C.