I usually post under DE mom to twins.
We used a known donor, and have sort of had the same issue come up with our donor and her mother. Our donor told me that once her mom had said that it felt like my friend was giving away her grandchildren, and that they should get to know their real grandmother.
Our donor very quickly told her mother that all she was donating was an egg or two, and she was in no way giving away a child, just a cell that she would have lost in a month anyway. And that yes, Molly's kids will know their real grandparents, Molly's mom and Brian's mom. End of discussion... that she wasn't to ever talk about it again in that context.
Firstly I really think that your friends cousin (the donor) needs to be the one to set her mother straight on it. I assume that she is their with her mother or is in the same general area. Or if your friend needs to call her cousin and ask her why she hasn't put a stop to or said anything to her mother about this.r
And lastly your friend may need to call and tell her aunt to stuff it where the son doesn't shine. Otherwise it may be best to to cut all contact and make sure that she can't get a hold of any pictures anymore.