Arwen when my DS & now DDIL married, both sets of parents contributed to the wedding and the couple made up the difference. Wedding invitations were sent out with the wording: Together with their parents X & Y would like to invite . . .
We had very little to do with the organisation, we made certain they knew we were happy to get involved when they wanted or needed us.
There were a lot of guests who the couple invited themselves, family on both sides, a few of our friends who had been around for most of DS's life, ditto for a few of DDIL's, the rest of the guests were their own friends - it was a joyous and wonderful wedding. I wish you, your DD and your future DSIL the same.
Muffin, I'm fast thinking you should blog or start writing a book!