Your 10 acres for the group is a whole lot more than my cow group has open at any one time! 

I am finding that instead of daily moves in my rotational grazing system I am giving them 3 or 4 days worth to provide more space for a calving cow to go off by herself.  Right now successful calving and bonding between cow and the correct calf is more important than a very tight grazing system.

10 acres seems like its large enough where you shouldn't be having pair-up problems.