Ivy flow full brood box

[deemann1]

All my hives are terrible busy the past few days with ivy flow , I removed all Queen excluder on hives and had a quick peak in some colonies..
My colonies are all on single brood now , still lots of drones about,I'm just thinking can these hives still swarm because there full of bees and nearly full of stores.
Is it ok to add supers this time of year let them go brood and half ?

 

[Beefriendly]

No reason why not. Although I would tend to put it underneath the brood box. It will provide parking space for the bees.
Their foraging time is limited in the autumn, mainly on warm afternoons, rather than all daylight hours as earlier this summer.