Hi, forgive me to respond on this, but I saw it and because I'm a teenager as well I hope I can 'help' you with this thing. Forgive me if it's nonsense, just trying to help
I think you should really try to break the cycle. My best friends fasts all day, cause that's the example her mother gave her.
You could show her how to eat on a healthy way, and how to enjoy food. (though you might not like it)
She must know food isn't your enemy. Now you're still able to convince her about that.
When my parents told me I should eat healthy and that an ED will stay with you forever I stopped losing weight and gained a few pounds.
Though it didn't work forever cause I was already too deep in it, it worked for a while.
If your daughter is getting an ED you should talk with her, tell her all about it, how it won't make her happier. Make receipts with her, show her that you can be healthy and thin without an ED.