I am trying to figure out how to handle a somewhat delicate situation. My fiance and I are getting married and are aiming at celebrating with 120 close friends and family. My parents are divorced and both my fiance and I have large extended families that we want to include. My mother was originally paying for the wedding completely, but now my father has agreed to pay for half of the wedding and we are including him with my mom and stepfather on the invitation. My stepfather is not paying for the wedding. My mother has said time and again that she really wants this to be a wedding of our friends and family and to invite who we want, not people we don't know.
My stepfather has taken a very keen interest in the wedding, much more than I would have expected (he has been involved with a few things that I thought would have just been handled by me and my mother). He is also very involved in organizing the guest list. And he has added to it. (Background: my mother met my stepfather during my first year of grad school and they were married the next year, I have only known him for 6 years. I also have two former step-mothers whom I no longer speak to).
He has asked that we invite his brother and his sister and their spouses, which we agreed to because I have met them on a few occasions and it seemed important to him. But then he also added all of their children to the list. This is what I had a problem with. Of the 7 people he added to the list, I have only met 3 of them, and only one of those 3 more than once. He also has a minor on the list when we have stated time and again that no children are invited to the wedding. I have a step sister and step brother who will be in attendance and have asked my stepsister to read at my mom and stepfather's instance, over one of my very close cousins. My dad's side of the family is only getting 10 seats total. To give 7 to step family I have either never met or met once seems odd to me. They have never tried to reach out to me and we have very little in common in general. He has also put his family over some of my own cousins who have had to be cut from the list.
I have explained that I would rather have them on the "To Be Considered" list and extend an invitation only if there is room. But this has not worked. He has literally moved them up the list and added them to parts of our already completed list.
Nothing I have done so far seems to get through to either my mother or stepfather and it is actually the biggest cause of stress for our wedding planning. My mother has told me to stop bringing it up and just deal with it, but it actually worries me that 5% of the guest at my wedding could be strangers to me.
Sorry for the length of this, but I will take any advice at this point!