Family weddings are so tricky when they say no kids. I would have the same problem as you because all my child minders are family. One of my friends had a child free wedding and she provided free child minding for all her nieces, nephews and children of out of town guests.

I know there are babysitting agencies that charge so much per hour for care - are there other people that you could put in with maybe to get your kids all minded as a group? It might be cheaper. But I understand entirely if you are not ready to leave your DD yet and in that case, just decline the invite. It would solve the issue of child minding and the present.