Family drama, help

We have a relative who is very toxic, she’ll immediately talk trash about anyone who isn’t around but pretends to be kind, especially on social media. About 2 years ago she was caught in several lies and tried to backtrack on all this drama that she created. She’s very manipulative and honestly unkind. Well I have to see her this week at a family event and I know she’s going to want to take a picture with my baby for her Facebook but I don’t want her near him or me. Any ideas on how to politely say you’re not holding my baby? Or F off in a nice way really? Lol