To blended family... Oil and water

I have been dating a guy for a year and a half And he recently proposed. (Yay!!)

We are having some struggles because he has a child from a previous marriage ( daughter is 11)... My biggest issue right now is that he has a tradition that he has had with his X wife that I not particularly comfortable with especially that now we are engaged... He goes to his X wife's house on Christmas day for around 4 hours to open Christmas gift with his daughter...( I think 4/hours is way to long of a time). Last year was our first Christmas living together and I felt some way but because I was just the girlfriend I didn't fuss that much this year I am suggesting she (x wife) comes over to our house since we have the daughter this year to open gift at our house with us.. He wants to wake up go to his baby mothers house with his daughter to open gift and then both of them come back completely leaving me out of that situation.

He is saying that I am coming between his daughter and him🤔🤔🤔. Am I overthinking it or do I have a valid point.

He wants to be a blended family when is convenient for his... Ie hanging with his married friends with kids, but I am not invited to any of his daughters shows, games,recitals etc. It's starting to make me have a serious disconnect to his child. Please help.