Does that mean you want her ability to be a secret from the rest of the group? That could be kinda fun. Also, I feel like Negan might be good at guessing when she's shifted as someone else. Not always of course, or right away...but if they're talking face to face he'd be good at picking up that it was her. Especially since he's all about reading people's expressions, and changing her shape wouldn't change how she reacted to things, or rather, fails to react to things in her case.