Families can be very strange especially when grieving.
My Dad died suddenly last year and I'm lucky that my Aunt (his sister) has stayed very close to me and my Mum, even saying that my Mum is like a sister to her. It's lovely to have as we have that connection to my Dad's youth.
My Mum's sisters, however, I've hardly seen in years. Saw them a lot when her Mum/my grandmother was dying about 14 years ago but after she died, that was it. When my Dad died, one of my Mum's sisters came to the funeral but hardly spoke (never spoke to me which was a bit crap as she hasn't seen me since I was 10). The other one emailed (!) 20 minutes before the funeral to say she was too busy and wouldn't be there.
In the past year and a half I've learnt an awful lot of people behave in strange ways when it comes to grief and death. Ways that really don't make sense to me and can often feel extremely unfeeling.
Probably a bit of a pointless ramble above there :o But if you ever need a chat, I'm always only a PM away