To tell him to shove his camping trip?

[Supercala123]

Myself and my partner have 4 children between us. DSD 9, my two DD 12 and 15 and DS between us, 1.
Partner doesn’t really get on with my DD (15), they barely talk to each other.
He has just said he wants to book a camping trip for two nights next week, first night just on his own with his DD and second night for ‘whoever wants to come’. It’s inevitable that my 12 year old will ask why she’s missing out on a night when DSD isn’t. It all just feels a bit shit.
AIBU to tell him to go and I’ll arrange something else for the other three and myself?

Do something special with yours and then all meet up for a family meal somewhere the following day or similar

Not that easy with a 1yo.

And a family meal with him and 15yo not speaking will be fun.