Long time lurker.
Try to keep this brief.
My sister organised a meal for my nieces birthday and to my knowledge invited my mum, dad and her husbands mum. They had this meal at a location near to me. I have just found out they invited my brother, sil and their kids! When I confronted my mum she said sister had mentioned the night before inviting me but she thought I might not be able to afford it!!! Am I being unreasonable in thinking she should of at least invited us?? I feel sorry for my kids as they love their cousins but are constantly left out. Being left out of birthday celebrations seems to be the final straw for me x