Yes, this is a very old thread. The op's gs will soon be 7.
Sundried, do you still read here? Have things gotten any better?
Nantastic, your dil sounds very controlling. I'm so sorry. But she may mean well. She may really feel that hosting would be "too much for" you, as offensive as that may sound. Also, she may see these occasions as a chance to "get in" everybody - you, her extended family, and yes, your ex. If you hosted, presumably, you wouldn't invite ex and then they'd have to celebrate with him on a separate day. They might not want to do that.
You don't have to go to all their events though. It depends on whether it means more to be with ds and the gc or to avoid your ex.
Have you tried inviting them - just their little family - ds, dil, & gc - over for a simple lunch or dinner, unrelated to birthdays or Christmas? Maybe that would work better?