Re: To combine or not to combine
Do not regret getting rid of the aggressive queen. If you are going to have bees, you may as well be able to enjoy it. Some folks like to suit up & work in a cloud of angry bees, but not me.
When you say "a month" , I'm assuming that is give or take a day or two? Because when you say you saw a new virgin emerge from her cell a week ago, that would mean approx. 3 weeks since you requeened? That's around how long it can take them to raise a queen, so it's almost guaranteed this virgin comes from your old queen. The new queen probably been killed straight off & they raised a virgin from existing young larvae. Considering the time frames involved that's the most likely explanation.
So you don't really want this queen heading up your hive anyway.
Just not seeing the virgin does not necessarily guarantee they don't have one so you need to check this before doing the combine. Easy, just give them a comb from the other hive with eggs, & 5 to 9 days later check to see if they started raising queen cells, that will tell you if they have a virgin or not.
If they are genuinely queenless you could do a combine, or it is probably not too late to introduce a bought queen provided you give them a frame or two of brood at the same time you introduce the queen.
They might be just nasty bees that are likely to always reject a new queen of different race, in that case you could do a combine, leave while so the old bees will die off, and then do a split & requeen.
44 years, been commercial, outfits up to 4000 hives, now 120 hives and 200 nucs as a hobby, selling bees. T (mostly).