Welcome to the board!
Just curious how long you and your wife have been married. I am wondering if before you were married, that you spent any time with your wife's family. I'd have to guess that prior to marriage, you attended some of the birthday parties, holidays, with her family.
Sounds like you all live in the same town or closeby, so traveling is not the issue.
You and your wife need to sit down and have a chat about this topic.
There must be 9 people in her extended family if they have birthdays from April to December. Everybody has birthdays. Birthdays must be a special celebration in her family.
Not every family believes in celebrating birthdays together. Perhaps your family was like this when you were growing up.
I was born into a large family and DH knew this long before we were married about my extended family (my parents, and 7 sisters).
Some families are not close.
Ever hear that saying,
"A daughter is a daughter all of her life.
A son is a son until he gets a wife."
Birthdays are a Big Thing in my family. It is a lovely tradition. My DH doesn't quite understand it, but he does know that it makes me happy. It was my Special Day and still is!
It's tradition to be with the ones you love for cake, ice cream, blowing out the candles, singing "Happy Birthday," opening a gift, sharing smiles, visiting, getting hugs & kisses on your special day.
Yes, you do need some traditions with just you, your daughter, and your wife.
You both need to calmly sit down and discuss which that you will have for just the 3 of you at home.
And with that, you both will also decide which of her family events you will attend, where you will be a friendly and loving husband (and not complain about attending.)
Give and take.
Marriage is a lot more about giving than taking.
Your wife probably feels like she is giving you 110% and you probably feel like you are giving her 110%.
Let us know how this comes out.