OMG - sounds like my family weddings...
When my niece got married we got an invitation that read: To The Rattray Family. I called my niece and asked if that included our daughter and her partner. The answer was...they can come if they want, but there's not much room.
There was all the room in the world. It was outdoors. what bothered me was that NO COUSINS from our side of the family were invited, yet on her mother's side, not only were all the cousins invited, but their babies (ankle biters), as well. Toddlers were everywhere!
It was an awful wedding.
If I had to do it again, I would still ask, but with the answer I was given I would say, then we won't attend either.
I can't even offer a reason for our daughter not being invited. She is the most wonderfully generous individual.
My personal view of your situation Klara is that, whilst you are there you will most likely be feeling hurt. Better to be upfront before the event. So you stand on some people's toes, but they are surely standing on yours right now. Best to you.)