Don't seperate. I never had any trouble with other does around, retired and spayed does were actually great aunties for the kits, taking off some load from the doe.
When nesting and kindling they are on remote control anyway, and the other does get out of the way.
I only make sure that they use seperate nest boxes, by blocking the tunnel between the hutches when the second doe is about to kindle, for a day max, and they still get garden time together.
I would love to keep the buck with the does like dlynn, but I don't need more than one litter per doe and year. Bucks can be a great with the does and kits.