Will try and stick to the facts. Changed name also but on here a lot.
FIL has big birthday end of May, 60. Back in October he said he wanted us to go away together so his two sons, wives and kids. We said back then that we didn't think we could afford it as my job contract is temporary and husband's contract was coming to an end in March. BIL and wife earn a great deal more than us and have multiple holidays a year. We suggested waiting to October half term when we'd hopefully know more about our jobs.
Would your parents or in laws go away with the other sibling anyway and leave the other sibling at home? AIBU and over sensitive or is it piss poor that they are all off on holiday together in August to celebrate and we can't go.