My FI and I have decided to not invite the children of guests who are not family. Nieces, nephews and cousins are all invited. We are doing this for a number of reasons - budget being a primary one. The other being that we have friends with 5 children under 10 years old who have the nasty habit of bringing their 5 very rowdy, completely undisciplined children EVERYWHERE and then pawning them off on others to watch. We would like our friends, the parents, to be there, but do not want their children to attend. So ... we made a blanket rule that no children outside of our families will be invited.
Then, we get a message from one of FI's close HS friends from out-of-state. She has 2 small children and a husband who travels frequently and is rarely home. There are no family members remaining in our area who can babysit, one of the children has special needs and the other is an infant. So, this friend all but said that if her children are not invited, she would not be able to come. FI really wants his friend to be at the wedding, as she is one of his only friends remaining from HS that he is still in contact with. (She even suggested we check with the venue to see if he can attend for free as he has special dietary needs and would not eat at the reception - she would pack special food for him.)
I have no problem making an exception for this specific case, given the extenuating circumstances. I am unsure, however, of the fairness to the other guests, given that nobody else's children are invited. (Granted, the rest of our friends are in-state and have babysitting available.)
Is this something I should be concerned about, or is making an exception perfectly fine on a case-by-case basis?