Welcome to the club!!
We went with the addressing to only the parents and it turned out OK for us.
However, my bridesmaid and her hubby (a groomsmen.best man) are due 2 weeks before the wedding but not intedning to bring the child as they know i want a no kids wedding. Her parents are coming down for the weekend to look after it but I went for a compromise and told her to get her parents to come to the ceremony and drinks reception to look after sprog and then take her away while she has her meal and then if she wants ot leave afterwads she can, but she's been able to enjoy her orle as BM (which she really wants to do).
On the other hand, the other bestman's Mrs is due 3 days before the other lot but they seem to think it's OK to bring their sprog sa it's a baby (to me a kid is a kid). I've decided to not say anything yet as anything can happen. Have that one to look forward to. Also, they're our mates so if I can't speak to them honestly, who can I speak to.