Michelle Rounds to Rosie -- I Want Full Custody … Of Our Baby Pictures

Rosie O’Donnell's divorce has gotten so bitter it's gone from fighting in divorce court to battling over the rights to Instagram.

Michelle Rounds is on the attack, claiming she took a picture of their daughter, Dakota, and Rosie had the nerve to post it on Instagram.

Michelle says the law is crystal clear -- she took the pic so she owns the rights to it, and therefore Rosie has no right to post the pic anywhere.

Michelle has contacted Instagram, demanding that the pic be scrubbed from the site. So far the company has taken no action.

Rosie and Michelle are both under a gag order, prohibited from disparaging each other in the media ... social or otherwise.