It's a long one but I don't want to drip feed... Wasn't sure where to put this as its a bit relationship, a bit money matters and a bit AIBU so sorry if I've posted in the wrong topic.
Backstory; I am NC with my stepmother, my dad and her got together and had 2 dc but I was never allowed to be part of their 'family'. The relationship between her and my dad ended and id be allowed to stay with her and my brother and sister for one week every summer and a few days over Christmas but very low contact apart from that. When I was in my early 20s she said something shudderingly unforgivable and I cut her out of my life completely; this meant having no contact with my half siblings as it would have to go through her.
So I have 2 half siblings but never had a family type bond with either of them and zero contact for over a decade. They are complete strangers to me and I wouldn't recognize them now.
Yesterday one of my aunts got a phone call out of the blue from my stepmother. It transpires that my sister is going to university but her funding won't cover all the costs (rent, transport, food, books, etc) and there is around a 4k shortfall a year. The course my sister is doing is very full on and not one that can really have a part time job running along side it. Stepmother was after my contact details as she knows my granddad left me a quite substantial inheritance and out of all the people she knows I'm pretty much the only one who can cough up the dosh without it really affecting my life/bank balance. So she wants to know if I'll cover the shortfall. My aunt refused to pass on my phone number but said she'd pass along the request.
I'm really fucking torn. I hate the SM has tried to get in touch with me, but, and it's a big BUT I'm wondering if I should transfer my sister some cash as a monthly allowance (so not a huge lump sum) as its a difficult course and I feel her degree is very worthwhile and I can afford it. But she's practically a stranger to me (last time I saw her she was 6), the request hasn't come from her, and I continue to want zero dealings with SM. But education is so important and I know I am fortunate to have left uni with no debt, and it's not my sisters fault SM hasn't saved towards a uni fund and can't afford to help.
So should I pay? Should I ignore? Should I try and get in touch with my sister to make sure its not some weird scam? And if I pay then is it fair on my other sibling or should I start paying him an allowance too?