Children attending wedding

Hello everyone I need some advice: Originally my fiancé and I were on the same page about not having children attend our wedding. Although after our first meeting with the wedding coordinator I said no kids in attendance and he is too nice sometimes and started talking about how we "may" have to allow his half sisters stepson and his cousins children also which would be 6 additional guests to our already very full guest list. I also do not want to offend other guests by saying no children but then allowing a few. I personally just do not want children at all because that is just the kind of day I envision for our day. He is worried about them not finding childcare as they are coming from out of state however I believe that is on the parent to figure out and unfortunately if they can't make accommodations then they simply may not be able to attend. Any thoughts or opinions on this please?