hmmmm....
Any pairs you have I would leave well alone....why rock the boat?
With regards group bunnies..... as a rule the more you have together the more squabbles, infighting and territorial disputes you are likely to get.This equates to hassle and in our experience in the long term , vets bills.
However there are so many variables such as temperament , size and type of buns, run area , hutch or accommodation area, proximity to other rabbits, dogs , cats ....you name it that trying to give an answer that will have any relavance to you is nigh on impossible so be carefull which advice you take. If you do go ahead though the more permanent space you give them with multiple hutches or accommodation so they can choose where to go and with whom then the greater the chance of success
Its a bit like renting a property as a whole or by the room. Rent it by the room and the chances are the infighting and squabbles between tenants will far outweigh the extra income you as a landlord will get in the long term.
Best of luck.
alan.