Battle of wills erupts over social media posts

DEAR ABBY: My adult son has a drug addiction, for which he is receiving treatment. My family and I have just met his daughter, who we had only recently learned about. She’s 6. I had a celebration for her birthday at my house. My mom (the great-grandma) took pictures of the birthday girl and her friends, and posted them on social media. I had asked her before the party started to please not post pictures of the children on social media. She said she does what she wants.