RSVP trading- should be illegal!

People never seize to amaze me. Yesterday, I received an RSVP with a name that I did not recognize, it was with my same last name, but I was positive that I did not invite this person because I did not recognize this name! I called around and I finally found out who it was.

A small portion of my family lives OOT in Ohio. Some of them I am close to and some I am not, but I invited everyone out of courtesy. My Dad's cousin (my godfather) who I have no seen in three years, just brought his children from another country to live with him (ages 16-21). Two of them arrived 5 months ago, way after I started planning my wedding and didnt even find out until 3 months ago that they were here. I find out that they were epxectign an invite for all his children as well, so out of courtesy I invited all four of them (him, his new wife and 2 children whom i've never met). So it turns out that his 3 kid just arrived and instead of calling me to see if it was okay to bring him, one of my Ohio aunts gave him her RSVP card (she is ill so she won't be attending, and I knew that so I invited her out of courtesy) and put he put his son's name on it! To me that is unbelievable and rude! All without even consulting me!