S.R.
Definitely invite them! Kids LOVE parties, and I know I love my kids to go to any party that they can, I don't care that I have to buy a gift, it's an outing, a social function and it wears them out!! And anyone who looks at it as an invite just for a gift is not worth fretting over their opinion to begin with, in my opinion. Kids need to be social and parties are a good was to start that. Good luck with the party!