Oh I see... They have previous. My english gran was not like that - she was a little innocent who saw people as individuals - but she wouldn't have know what diwali was. She never gave my mum meat but I do remember clearly that she gave me bacon sarnies when she looked after me which I loved when I was in primary school. Mum had no problem with it. Gran died in the early '90s and I still miss her.
I now think it's really less about your faith but rather trying to get your culture a tiny bit of affirmation from ils who are cold and disapproving and racist.
Dunno what you do but I think you expecting a phone call just not worth it. A lip service phone call at diwali isn't affirmation. They need to start treating you as a valid individual.
Can I also say my dh has never once given me a diwali greeting - he knows perfectly well when it is. I go along with christmas because it's all around us and it's nice (I'm not religious btw). He's from a culture that's very dismissive of other cultures.
I hope your dh can support you in this like my df was with mum.
But mum didn't do a veggie household as she was in the UK and wanted me to mix with the general population who ate meat. She grew up veggie - does eat meat (never beef) but has a meat eating culture (although she doesn't seem to eat it herself. I know lots of people who are veggie (animal rights) and also vegan but don't do it for their kids.
The name thing - ok -well my ds has an italian surname so I ensured there was a first name that was english and also Italian. Harder with Indian names, I know. I got around it by using middle names which were grandads' first names - to placate.
I'd suggest that if you need to host christmas you have both a vegetarian and the old traditional whatever ils like (turkey?) and if you struggle to be involved with meat, your dh can cook it. HOWEVER, the deal is that if they host christmas lunch they ensure there is a decent vegetarian option - it's called inclusive. It's not hard.
I cater for veggies and also non pork and it's really very very easy.
I've celebrated christmas with my mum's family and mum made both meat and veggie.
Best of luck. You're doing your best and they are still difficult - acknowlegment of your faith celebrations is of zero importance imo when right now you need acknowledgement that you are the mother of their dgrandkids.
You should accomodate their meat eating (at christmas etc) and they must understand you are a vegetarian and cater for it.
If, as a household you go vegetarian - understand that they'll think their ds is doing it for your religious reasons. Have you planned for this?
Can you live somewhere very far away from them?