This concerns my older sister and her fiancée. She is late 30s, he is mid-40s, and both are on the autistic spectrum but not officially diagnosed, but both live independently, hold down good jobs etc. Sister openly admits she's on the spectrum and understands she sees the world differently. Her fiancée doesn't/can't/won't acknowledge it, and his poor behaviours/social mis-steps are always someone else's fault.
For Christmas, I asked my mum to make me up a hamper of foody bits as my present. She did as requested. Went to a lot of trouble to decorate a box nicely and filled it up with a mixture of food items, household bits, and a couple of jokey items that she wrapped up. I really enjoyed looking through the hamper, unwrapping the bits and bobs and it was just nice all-round. It was just mum and I for Christmas day, so sister and fiancée didn't see my reaction to the hamper.
A few days later, sister and fiancée turn up, and mum has done a hamper for them as well. They hadn't asked for it, but neither of them told mum what they wanted, so she just did the same as she did me.
They both sat down on the floor to open it, mum hovering over them expectantly, expecting a bit of a pleased fuss, like I'd made.
Sister was virtually silent, fiancée just went, "Oh, sponges, I've got loads of them." They spent maybe a minute poking through it, didn't say thank you, and then just went back to their seats on the sofa. Mum looked a bit disappointed, but didn't say anything.
My question is, would I be wrong to say anything to my sister like, "did you thank mum for the hamper?" I just know that mum put a lot of work into it, and their response was underwhelmed, bordering cold.
I KNOW they're both autistic, and social norms pass them by a lot of the time, but they're reasonably functioning, established adults, and SHOULD know how to behave appropriately to a gift that someone has obviously put time and effort into. But is it my place to raise it with them? I know the answer is probably "not your problem", but I'm very protective of mum (more so since my dad died in 2017) and hate seeing her disappointed by my sister.
There is more to unpick, like I feel that my sister hasn't pulled her weight in supporting mum since dad died, or while he was ill in the year before he passed. And I totally see that is a contributory factor as to why I'm cross about something like a Christmas hamper. It's a little bit the final straw in a long like of annoyances!