FI's family finally gave me a list of who they'd like to invite yesterday. Most of the list was who I expected. I already had his aunts, uncles, cousins, and grandparents on the list. The new ones are some family friends (more than I expected but I figured my parents are inviting some of their friends so FI's parents can too). Today FMIL gave me a second list of even more people she said FI's grandma wants us to add. These are all his dad's cousins and their kids (I don't even know how many of them have SOs). One of the people on the list FI doesn't even know how she is related to him. I just feel like this could really balloon out of control.
We are inviting ONE of my mom's cousins and his family but he is performing the ceremony and my mom is actually close to him and his wife (they talk on the phone on a regular basis and text all the time). Would it be rude to say we don't want to invite FFIL's cousins and their kids but still invite my mom's cousin? Apparently, FI's grandma claims none of these people will come but if they do it's going to make a big difference with the budget for people we hardly even know.
ETA: FILs are not contributing to the wedding at all. They have offered to host the rehearsal dinner and have made comments about potentially covering one or two small (less than a couple hundred dollars) extras for the wedding.