Just sympathy from here. These things happen and are heartbreaking, frustrating and challenging.
I had a guard donkey once, who had been running with a group of Boer goats. All were white with brown head. Moms kidded, babes in field, all good. One day a young kid from adjacent field crawled thru the board & hot wired fence. All that field and this kid were traditionally colored. She killed that kid.



Never bothered any from "her" herd. All look alikes.
Sometimes we can't win. Sorry for the lost lamb.