Yep, thanks for the further info after my typing was slower than your previous response!
The later posts seem to have covered your problem.
I think you will probably finish up uniting. Diffficult, so late in the season, to get any strength into the colony, and stores for winter.
I am now presuming your colonies are on standard National brood frames? I keep thinking 14 x 12 these days, so 4 frames to me is considerably different to 4 frames on standard depth. I also note 'on' and 'covering' in different posts - and the two can be somewhat different in my book.
With one full colony it may not be too easy to deprive them of brood to boost the others at this time of the year.
Again, so many variables in beekeeping, but hopefully you will get sorted before the time for winter clustering. One way or another.
My advice is always don't run before you can walk. In my early days, I expanded colony numbers and failed. BTDT. I now expand early, have strong splits or nucs, to defend (against wasps) later in the season and am prepared to sacrifice numbers of colonies for strength at the latter end of the season. With very few colonies that is much more difficult to achieve, I know.
Regards, RAB