Hi,
Are any of your queens marked or clipped?
If so, they are easy enough to spot early in the season, less bees.
I wouldn't do it yet if your weather is still cool as you will have to open to find queen.
I don't inspect until April myself as weather still cool here also.
Anyway to unite one with another, one queen will have to be removed.
Normally the queenless colony on top. Sheet of newspaper with a couple of small slits & q excluder. Bees slowly chew their way through. They unite slowly.
Are your hives beside one another?
If all these queens are good queens in lay. There might be a beekeeper that would take the ones you don't want. Are you with a Beekeepers Association? If so, contact them to see does anyone need a queen.
Wait until your weather is better i would say anyway first before doing anything.
Regards
Sharon