Do I have to invite them to the rehearsal dinner?

We are having a rehearsal dinner at an expensive restaurant the night before the wedding. Three of my fiance's groomsmen have 2-3 kids each. We aren't close with the children, do we have to invite them? Do most parents just leave their kids at home with a babysitter that night? There will be other children there, but only our nieces/nephews and they are part of the wedding.