Having said that, the DGC are my DGC just as much as the DIL's mum and sometimes you do feel left out.
Everyone has a story. Mine is that they treated me like crap. The whole family looked at anything to try and say I slighted them. In our culture, when you walk into a room you greet everyone. Apparently, after I greeted everyone I was supposed to sit with them. I only came to visit their son. I'd go and see him and we would leave. That was a problem. His sister actually admitted 4 years in, that when we said we were getting engaged (2 months into the relationship) she told him I wasn't right for him, but she was wrong. Great 4 years making me feel like crap and unwanted, treating my family like sh*t.
when we were pregnant with their first DGc, my DS, They came to the hospital once (CSection - in for 4 days). then within two weeks had jumped on a plane to retirement house.
at the time I thought, well maybe they felt my family were going to be with me. but the idea that you would come especially for the birth and be booked to leave within 3 weeks of the due date (he was two weeks late). however when their DD had her first, they were here before, during and after.
Roll forward and Sil and I are pregnant at the same time. the children were due six weeks apart. the booked to leave three week's after the birth of DN. Just a sorry they couldn't stay longer (so much to do back home I imagine). Would you believe my D's came four weeks early and Do you know where they we're? on a plane. my D's was in hospital till her due date.
And for me the final pill to swallow are my kids cards. Just last week she delivered cards to my children E.g JT and BT instead of JR-T and BR-T. she even rights it inside the card who needs their surname written on a hand delivered envelope much less INSIDE the card. Who does that?
then she asks why I don't call her mum. Short answer, my mother has never treated me like shit. Has never had to get used to me and oh, because she's my mum.
I'm sure you have a story. I'm sure your DIL has a story. For me jumping on a plane after your first DGC is born was never going to help relations.
Tbh you sound as bitter as I feel.