Holiday schedule nightmare - Thanksgiving is in 8 weeks

We're supposed to alternate Thanksgiving but my parents are having a huge family thing this year (first time in 5 years because my dad was sick). I have the kids Thanksgiving 2024 per the custody order but I'd really like to take them. My ex is already planning something with her new husband's family. What's reasonable to ask? Am I entitled to ask for a swap? How do I even bring this up without sounding entitled?