Persistent uninvited guest, what to do?

Hi everyone! Looking for some tips, please help 🙏🏽
I have an ex aunt who I haven’t seen or spoken to in over 30 years, but we are friends on FB. My uncle (by blood) and his long time Gf along with my cousins and their spouses are invited to our wedding. Not sure why but this ex aunt wants to come to our wedding. Not only is she an ex but my childhood memories of her are all the trouble she was to our family. So I heard from other family members that her daughter, who is invited is going to swap her husband for her mom. There is no way of doing this on our RSVP so if she doesn’t ask us I’m sadly assuming she will just show up day of. We will have a guard checking ids to guest list so she will not be allowed in. I just don’t want to start a family war for sticking to our plans. Oh and we’ve even started an Instagram wedding account strictly for guests where we are posting updates and q & a, etc. so everyone knows our guest list is final.