Preventing swarm absconding - headed by a virgin Queen

[SteveHLD]

Here is my story. Both the Queens in my colonies had clipped wings and both colonies attempted to swarm at much the same time. Prior to this my landlord gave me 9 hours notice that he was going to do major works next to my hives and inevitably the bees felt very threatened and the builders very sore and having moved the Bees I missed an inspection.
11 days ago I destroyed all but 2 closed QC in my better hive A and transferred one QC to a Nuc to requeen hive B. I kept 2 cells in A as I wanted to increase my chances of having at least one colony even if size was reduced by swarming.
Then the weather turned grey until ...
2 days ago, lovely warm & sunny. I assumed that that was when Q would mate.
Yesterday, unpleasant weather back again and I hived a swarm that had settled all along a 6 foot post adjacent to my apiary. I put in a QE to reduce the chance of them absconding but I appreciate Q might be able to queeze through. So she may have mated or mated not? would she look different if mated? I have no open brood. I will give them some sugar solution this afternoon. I suppose I need to remove the QE in case she has not mated but should I delay to see if she starts to lay once they have made some comb? If I fumigate them with oxalic acid do you think it will make them more likely to abscond? What do you recommend?

 

[drex]

She will not be able to get out to mate with QE in place, and if unmated how is she then to lay fertilised eggs? Your profile says you have three hives. If you took open brood from the remaining hive and add to the one you are worried might abscond, that would tie queen to the box. In my experience they are more likely to abscond in first day or two, but it can happen in an established colony too.
I would now remove QE.
Not exactly clear what happened in your hives, but, Clipping queens, cutting down on queen cells, putting in QE etc will not quell the swarm urge. That is only achieved by some sort of split as in an artificial swarm.
I would only vape once she has started to lay, but before the cells are sealed.