We live abroad, DS is coming home for Christmas / 18th birthday. His flights have already been booked and paid for. Now Dh wants us all to fly to Uk as we've been invited to his relatives for a family Christmas. This will cost a lot of money we can't afford and will totally trash Ds' birthday plans with his friends and mean he spends his 2 weeks holiday flying back and forth.
It's clear to me that it's a non starter but I know if I say it as it is Dh will feel un emancipated and start to dig his heels in.