Thanks everyone for your replies so far
I wouldn't put 'offspring' on the invitations of course, I would use 'children.' Right now, I am still on the fence about this, will have to talk to the FH again, as he has a say in this as well.
Maybe I should give you a bit more background as well: We are definitely having one child at the wedding ceremony, my FH's little niece, she will be our flower girl. They will be traveling from another province so they will definitely be staying. Her, I am fine with, as far as other people's kids go, they start to drive me up the wall when they start whining and get louder and louder as they try and get their parents attention. I don't have any children myself and would rather keep it that way, but my FH thinks differently.
And yes, I do feel like parents would be missing out on a night of fun, but you are right, if they did want to have a fun night out, they would find a sitter. I've gotten lucky one friend of mine will leave her two boys with her hubby and come out to the wedding (I don't get along with her hubby) I explained to her, even though I would like to meet them, the wedding isn't really the time or place, I would rather have her there and have some fun. She agreed and said since they aren't that far away that some time she will bring her boys in for a visit so I can meet them.
Why is this soooo hard?