I also welcome you here. You have been given great, great advice so far. The list that toothfairy has given you is really, really, helpful.
FoodSupport_AUS hit a nail on the head here: "16 yr old, treatment since Jan, no changes in weight and behaviors worse." She has to gain no matter what. What can we do to help you get the calories in and more and more in ASAP?
We did blind weighing and I think it really depends on the child and family, tbh. Torie's D needed to know to help her. My D never cared about the number. She would just ask if she gained or "did I do good, mom?" and no matter what, if the weight was up or down I just said that she was doing great. There is a post around ,I think toothfairy posted awhile ago ,about blind weighing and the professional suggested "no" to blind weights. I, personally feel that, blind weights may play a role at a certain point in treatment, and then to help them conquer their fear of weight, as FoodSupport says, then you can open weigh. I don't think it is as "black and white" as do one thing and not the other. You really could do both, depending on your situation and where you are in the journey.
I really believe that the exercise and I mean all the exercise needs to stop. " Was an althlete, cut training back to 2 x week. No other exercise, but her twin reports ED twin sometimes runs on the spot, and tried to go For long walks when she feels that she has not moved enough. " I think what she is feeling here is ED, ED, ED! We had to stop all exercise and I mean all. MY D 11 at diagnosis, stood all the time. We had to stop that and now she says she "hates cardio". These kids are the greatest, hardest working athletes and academics ever, and that can be part of their ED.
We can help with ideas to get her to stop exercise. I feel that the training has to stop too even twice per week. If she had cancer and sick she could not do exercise, let alone training while ill and in treatment. I echo Mamaroo, in that she needs to stop PE too.
toothfairy has a lot of videos and resources on exercise, "if it were cancer", etc... Please look them up they are a great way to start thinking about ED. YOu will need to parent so differently and it may be uncomfortable for you at the moment to consider that. But it has to happen to help her.
You need to throw out all the rules you had as a parent. You need to be in control, not ED. I am blunt as until there was a paradigm shift in my thinking,I felt powerless. Once I "got it" then it became better for me, to do what i needed for my D. It was not easy at all.
It is worth it, and it does really get better. It is really like climbing a mountain and taking switchbacks on a steep slope. It is so hard, gruelling physically and emotionally but when you get to the top- it is such a great feeling - and you can look back and truly see what you have accomplished.
I am sending all my support,
Food+more food+ time+ love+ good professional help+ ATDT+no exercise= healing---> recovery(---> Life without ED)