I’ve got a weaker hive that I’m considering to join to a strong one before winter hits.
Having done this before am quietly confident but am looking at joining onto a flow hive super.
Is this possible?
Would it be the same technique?
My supers are the full depth with 7 flow frames so am unable to actually place normal frames inside.
I’ve only ever joined weak hives so only had a brood on top of a brood.
I think I would take the super off first. If you are expecting more nectar before winter, you always put it back on again after the merge. Are you using a queen excluder?
What would I do with all the bees in the super when I remove it?
Do I just put it to the side until they merge?
How long?
You can either put a bee escape under the super to clear the bees out, or you can shake them off the frames back into the hive. A simpler option might be to “double newspaper” it. In other words, take the Flow super off and put a double layer of newspaper on top of the lower box. Put the weak hive box on top, making sure that you have dispatched the weak queen. Put another layer of double newspaper on top of the weak hive box, then put the Flow super on top of that. If you are using a queen excluder, put it on top of the upper brood box. 
Yes, if you have shaken all the bees off the Flow frames. It will only take a couple of days for them to merge. If there are any stores in it, I would wrap it in something like a large trash bag to stop robbers from stealing them. However, you may just prefer to do the double decker newspaper I described above. 
I joined a weak queenless swarm with a strong hive by simply using the newspaper method (2 sheets) on top of the super (standard super) of the strong hive (resulting in 3 boxes). Only later did I read to add it onto the brood box!
The bees chewed through the newspaper in a couple of days and there was zero death and fighting. I could see by the different coloured bees coming from the hive that it all worked well.
If there are plenty of bees in your flow hive I don’t see why it shouldn’t work just fine, though as I am quite new at this and I guess it could have been a fluke 
That makes sense.
I’ve used the newspaper method for a box on top of a super.
Putting the weaker hive between the brood and flow hive super sounds excellent.
That way the hive would be well strong enough for the winter.
One more question.
When all the bees have settled in and I want to remove the weaker hive and frames, I shake off any bees, what do I do with the frames and wax?
Just melt and clean them down?
Thanks
That is up to you! If the frames are fairly new (less than 3 years or so), I would freeze them for 48 hours. That kills off any wax moth and SHB eggs or larvae. Wrap them tightly in plastic and save for next season. However, if there is brood in the frames, I wouldn’t store them. In that case, you might want to put the queen excluder below the weak hive box, so your good queen can’t start laying up there. Within 3 weeks any brood in the weak box should have hatched and you can then do as I just suggested. If there is drone brood in the weak box, you will need an upper entrance, otherwise the drones will die trying to get out through the queen excluder.
I like to keep frames of empty comb if I can, as it saves so much work for the bees and gives them a real head start when they are building up.