Search Results: getting her a present as a friend

My friend Amy had this issue with her now fiance's mother for nearly 3 years. They just got engaged last month.

They started getting along from the start but when they were 4 months into their relationship, apparently a family member spreaded some rumors and made the mother and a couple others believe her. Then her bf's mother would proceed to gossiping to others about her, not invite her to reunions anymore, trying convincing her son to dump her and instead date an old ex girlfriend again... getting to the point of directly insulting her (calling her a golddigger, disgusting whore, how she'll never be good enough and literally said ''quit with the crocodile tears already'' as she was in tears).

My friend would spend time crying during that time and was very stressed out, couldn't explain what exactly she did to her. The guy at some point stood up for her and he moved with her.

The lies of that person were discovered and the guy's mother has been trying to make it up to her. Supposedly they reconciled just this past Sept. My friend explained that all though she forgave her, invite her to their wedding, they get along now and even wished her Merry Christmas along with the present (the mother did so too), she feels the wound is still fresh and needs a bit more time to completely get over it.

Backstory:
I have a stepmother. She had two kids with my dad. She hates my mother. I can't say why because nobody likes to tell the truth (or at least they're all very good at making lies LOOK like truth so I can't figure out which story IS). I live with my grandparents because my parents both suck at parenting.

It's my birthday in five days. I'm turning nineteen and my grandparents are taking me to their holiday house in Apollo Bay. I don't know what the plans are, but that's what's happening this weekend. Mum has opted to cook dinner for me.

I called dad today because I missed a call three days ago, and asked him if my younger siblings could come to Apollo Bay as well.
At first he was optimistic, the only thing getting in the way of them coming would be my stepmother.
Then I mentioned Mum would be there.
And he told me it was not worth getting my hopes up.

My stepmother, would refuse my younger siblings to visit me for my birthday, simply because my mother would have the audacity to be present for her own daughters birthday. Dad didn't even CALL me on my eighteenth, which, is considered a pretty big deal, to be turning eighteen. But no, why call? Why would anyone phone up their daughter on their big day?

I don't get to see my younger siblings often, I've seen them twice this year. The last time I only got to see them for half an hour because my dad is apparently more willing to fight to have a fish tank in the loungeroom than he is for his daughter to stay one fucking night.

Anyway, my question is, is it immature for my stepmother to refuse my siblings to be able to see me, just because my mother might be there?

Or am I just getting upset over something I should have expected?

(If you want further examples of what my stepmothers maturity levels are, she got angry with me, just because I was the typical teenager who spoke to her friends about her parents. Why would she worry about anything I said, if she really thought she'd done nothing wrong?)