First off, I’m glad to hear the babies are doing well. I hope that includes the two that you reported were smaller than the others and were having some trouble getting enough milk?
I agree with @Tobyluv – the best thing to do for all the buns, not just Minnie and her babies but your two new bunnies – is to keep the two newcomers physically separate (as in separate rooms/areas – I wouldn’t even think of pre-bonding at this point in time) from Minnie and her kits, until the kits have all been weaned, Minnie has been spayed and has had time to recover and let the hormones fade out. That means roughly, I’d say, three months or so, probably more. Minnie needs to concentrate first and foremost on bringing up her babies in peace and quiet until they’re ready to go their own ways.
And by the way, I recommend that, if you haven’t already, you start giving serious thought as to where the kits should go once they’re old enough. If you want to keep any of them, you’ll need to start planning for the pre-bonding and bonding process between and among them and with Minnie as well as your two new rabbits, if you choose to do that, which means you’ll need to have them spayed and neutered when they’re physically/sexually mature and are robust enough to go through the operation safely. If you choose not to keep them, you need to find good homes for them (and make sure their new owners/guardians will do the right thing and get them fixed), or turn to your local rabbit rescue for help.