Friends closer to each other than I am. What do I do ?

So I’m meant to be going out with my family friends to town and honestly if it wasn’t for my sister, I wouldn’t have been invited. My sisters much more closer to the friends than I am, and I’m pretty much only invited because of how I’m related to her. Other than that, if I go or don’t it doesn’t really make a difference. However I do like them, and they are there for me when I need them but other than that, that’s pretty much it. We all had a group chat together, but later on no one talked on it for months. And It wasn’t long till I realised my sister and them made a separate group chat without me. I later on brought it up to my sister and she said it was because they were talking about one of the girls in the groups uncle. I just went along with it but honestly there was nothing about the uncle I couldn’t know. They know if I knew about something I wouldn’t tell anyone.

But now they’ve arranged to meet and I had no clue because they’ve gone and done it on their own little group chat and my sister just told me. I do hate doing these little meetings sometimes because 90% of the time no one talks to me, or they’re talking about something I don’t know, and I feel pushy asking what they’re on about.

This has been happening to me ever since the start of time🤣and it’s not like I can get rid of them or refuse to go because our families are friends and that’s never gonna stop. I love them but it hurts really bad not knowing anything and being left out all the time. I know we’re always going to be around in each other’s life and I was wondering if anyone knew how to make the being left out more bearable.

well in my case i am the sister whose closest to the friends, my older sister who is invited might feel the same, but she has started making other friends so shes fine with it. i make sure not to intrude in her friendship with her new friends so that she can spend time with them more than me.

i suggest just try and look for your own friends who have the same interests in you