Family Christmas plans. AIBU?

[ShellyT17]

Boyfriend's sister keeps changing Christmas plans. Originally, boyfriend, boyfriend's sister and their mum having Christmas Dinner together at boyfriend's sister's. Then boyfriend's sister has argument with their rmum so my boyfriend invites his mum to mine for Christmas day.
Then... Boyfriend's sister and mum make up so it's all back to the original plan and my boyfriend then invites his mum to mine on Boxing Day instead.
THEN... Boyfriend's sister decides to go away for Christmas and my boyfriend now wants to invite his mum to mine again Christmas day! AIBU if I say no? Fed up with being messed around and have already ordered meat for my son and I. We just want a quiet one without all this fuss and changing plans every five minutes.

So...when these people all fall out you are second choice ...without consulting you first. When it's all on at boyfriend's sister's for Christmas are you and your son also invited? If not it's even more of a cheek the way you are constantly picked up and put down again. I don't think I would be playing ball.

Wtf so your boyfriend has invited his family to be catered for by you twice without asking you and they have backed out both times when a better option was available??
YANBU and I suspect need to replace your inconsiderate boyfriend with the New Year