I always think if you decide to have a destination wedding, it should either just be the two of you, or you pay for any guests you want to attend, it is just rude expecting people (especially close family) to pay a fortune to attend your wedding, especially if you then say they have to stay extra days!
I had a child free wedding, but fully understood that some people might not be able to attend, likewise understood friends that had moved abroad, couldn't attend either.
However, if you want family to attend a destination wedding and they have young children then much as you might like a child free wedding, you have to accept that, that probably isn't the best idea.
OP if you are happy to go to Croatia and can spare the time and can afford t, then I might do as others have suggested go as a family, but you only attend the ceremony, and then the rest of the time you spend with DH and DD having a nice holiday. Maybe meeting up with parents at some point.