Yes, you must RSVP because there will be a seating chart.
We love your kids! However, we want our wedding to be your night off. The reception will have lots off alcoholic beverages and adult music, so we are asking that you please find a sitter.
If your invitation says "and guest or a certain number of guest on it"then yes, if not we would prefer just you, due to seating.
Cocktail, please. No jeans please!