So my DS's are 5 and 7. The are in a sports team. There's 10 boys in the team in total. It was one of the other boys birthdays last week and unbeknown to me the mum organised a party for the team but didn't include my boys. I only found out about it as one of the mums mentioned it in the team WhatsApp group the day before (in error I'm guessing) and a few of the other mums replied making it obvious their child was going. The day after the party the social media post and photos with all the kids appear. AIBU that this has upset me. I know it's upto the mum who she invited but I could never do this. My boys are clueless so far, but I'm worried the chat at the next training day among the kids will be party related and they get upset that they missed out/weren't included.