I can't tell you all enough how much I appreciate your input!

Like all kids in her situation, Ashley would like to be in one place, with BOTH of her parents. But it isn't likely to happen. I had a real good talk with her mother this morning. She plans to have a good talk with her ex, but he isn't generally supportive. Ashley says he always gets home really late (as well as seldom there in the mornings).
While at daddy's house, if auntie isn't there Ashley and her brother are in the charge of dad's "wicked stepmother" girlfriend. She has two teenagers, and the reed-thin girl may be going through this and teaching Ashley. But Ashley's mom promised to watch for signs ... she hadn't noticed any, just that the kids are awfully lax about everything after a visit to daddy's. My daughter knows the signs much better than I do, since she went through that same thing - severely - just before her divorce. Her sisters have "ganged up" on her about it, and helped her quit. But it's one-day-at-a-time for her. She still "feels" fat, though she's finally back to a normal weight. She definitely doesn't want her daughter going through it.
Grandpa had a long talk with Ashley last night about the damage she can do to herself. After not speaking to me all afternoon (she was eavesdropping at my door and heard my conversation with her mother early yesterday), Ash came and gave me a hug, and later asked me to tuck her into bed. Today - so far - she has been quite good about breakfast and lunch. Her portions are small, and I keep reminding her to "take another bite", but as long as she stays there and digests the meal I'm happy. Her mom knows about the running to the bathroom, and was surprised at what I found out. Maybe mommy is in denial over her little girl; but if she keeps a closer eye on her now that I spilled the beans, maybe we can stop this before it really gets too far.
I'm having a better feeling about it, though. About once a week, I plan to drop the kids a note (with a return SASE) and subtly prod their conscience. I have an old silk shirt from Grandpa that Ashley fell in love with.... maybe if I give it to her as a reminder .... Also, I need to get hubby to copy a food-serving chart that I can turn into a couple of magnets: one for mommy's house, and one for daddy's house.
Believe me, I'll be reading all of your posts over again. If there's anything I can do to stop this, Lord knows that I will.