AIBU siblings and my DCs - are my expectations too high?

[Stepmooster]

Hi, trying to keep this simple. Sister and I not amazingly close although improving since we both had DC1 each in last year. My DC is slightly older and birthday get together has been arranged. Sister knew I was planning something for family and close friends as we don't all live near each other and we hardly meet up.

Her DH sent me a message that they will be away on holiday during DC1's birthday.

I might add our mother died less than 2 years ago, although she was a narcisist and my sister and I had no contact, it did hurt us both. This means my DCs 1st birthday (and all the photos) will be full of DH's family. My dad will probably be there but that's it.

I'm very sad for my DC I thought sister and I were going to make effort to not let the family fall apart for sake of our DCs. If she can't plan her holiday around important family events, then I should I be investing a lot of emotions and time in trying to keep us all in touch?

I should imagine that she will do something for her DC and we will make the effort to attend, but it does seem like its only me who thinks about family get togethers and xmas and birthdays.

My DH is a bit peed off too, are we being unreasonable? Is it normal to expect your siblings to make first birthdays especially when we haven't done the christening thing?

I was reminded of FB DS's first birthday.

PIL couldn't come as FIL was very ill with asthma/chest infection/allergies. Mother rang and told me that as PIL would not be coming, they would not come either as it would not be fair. So there was noone.

Left speechless.

We had a little party with some people I had met from toddlers who we didn't know very well and it was all a bit embarrassing really..........

We see each other 2 or 3 times a year as we all live hundreds of miles apart. we get on really well when we do see each other and we phone each other every week or so. I don't think I've made any of my nephews' birthdays, especially if they are during the week.
I usually remember to send a card and present though.
I never had aunties and uncles present at birthdays when I was a child (again because they lived several hours away) so don't regard extended family birthdays as normal. Preschool age we just celebrated in our small family unit, when at school they wanted their friends round.
I think families work better when you treat them like friends.
Getting upset because your sister didn't visit your granny as often as you wanted her to does make you sound rather controlling.
Expand your social circle so family get togethers are less important to you.
It's nice for families to meet up, but only if everyone wants to meet up and they're doing it out of love not duty.