H.H.
Mine also steps on toes. She is a helicopter mom and steps in all the time with know-it-all parenting advice and judgment when her daughter is a year younger than mine. Once I almost exploded. But I held back and am so grateful I did. My mother had a sil like this and I have one and I think its best to either bring it up with her privately and respectfully, or let it roll off you. If you fear you are going to snap then definitely bring it up before that happens. Look on the bright side: everyone sees her for what she is and what she is doing. Take solace in that and try to find some humor in her outrageous behavior. If you feel the need to bring it up, do it in persons, not in writing.