Once it was accepted that it wasn’t anorexia (which was hard) they offered us weekly sessions with a psychiatrist and a nurse. They never weighed dd again after that previously they had been doing it weekly and it was a huge problem.
They advised things like getting her to do baking for other members of the family , with the instructions that it wasn’t for her that she was baking for others (this was to just get her comfortable around food) , they asked us to take her food shopping with no expectation she purchased anything for herself unless she requested it and to make her food shopping sessions separate.
They talked a lot about safe foods, we slowly increased portion sizes they told us categorically do not suggest trying anything new. She was eating dry cereal for breakfast and plain GF pasta for lunch and dinner , after 2 weeks they asked us to try to introduce a small bowl of cereal after lunch for a week and then to do the same after dinner after another week.
They suggested a multivitamin and mineral supplement and basically persuaded her it was medication not food and she agreed to take it.
She refused the high calorie drinks they offered as she was strictly vegan (and GF and brand specific .
We were advised if she wanted to eat alone in her room that was also fine not to try and get her to join in family meals (but just to be vigilant in case food was hidden ).
It was horrendous for about 18 months then gradually got a lot better . She still only has a narrow range of foods she will eat (dry cereal one type only, plain GF pasta, soya milk, innocent smoothies, smooth soya yogurt, GF crackers and Granny Smith apples )