Just monitor them... there will be some pecking order to establish... make sure no one has any obvious unmilked quarter... so no mastitis... and watch the calves so no one looks like they are getting shortchanged... they will learn that if one goes on the cow, usually the natural calf... that the others better dive in and get theirs too... I think it helps to get them to learn to eat grass/hay/grain too... they will play together, and lay around and be buddies together...
When I had 6 with calves it was a circus for the first 2-3 weeks, getting calves on each cow...I would kick the cows out in the evening to graze (more than 12 hours over the night shift) and then bring them in, in the barn, in the morning.... and make sure all the calves got on the cow they were first grafted on... then I just would bring them in and first come first served... most would go to "their cow" ..... once they got it figured out, then started letting them out days with the cows so I could watch them... most would come in to the barn when the cows came in... after a couple days... they stay out all the time... If I called the cows to the barn, they came in to eat... The calves had figured out the creep gate and came in the barn when it was hot, and for grain... as the barn is "home".... makes it easy... This time of year they don't even come in for grain as much.. and they are all laying around in a group most every time you see them...