the buck won't hurt the kids, not intentionally.
I have my buck with my does all the time EXCEPT right after they kid.....yes he was in the pasture while they kidded out.
I do not pen up until after they kid....then I put them in a stall for at least 3 days for them to bond, be sure kids are nursing, doe is fed and fine and kids get good standing on their feet. Being so little I give them that 3 days to know Momma.......then out in the herd and they do fine.
When all my does kid out (all the same time--have only 30 now)---then I put the buck in his own pasture for about 2 months. I want those does not being bred, sniffed, bothered by a billy. Yup, he sure bothers them and it is most important to give the kids their time with Momma. And after 2 months when kids are are 1 month from being shipped to sale, I put the buck back in...he doesn't bother the kids and the kids are more than stout enough to move out of the way and such.
just what I do.