i’m so sorry you and your family are going through this.

this may sound kind of crazy but have you considered trying like really puffy clothing? like in the movie a christmas story where the snowsuit is so puffy that he can’t put his arms down?

doing something similar, or finding a way to keep her arms straight (you’d have to make it yourself) but a jacket with boning in the arms so she still can move them around but can’t bend her arms to be able to reach to scratch her face or neck?

when my sister was a baby she had it all over her face and my mom used to put a mini travel pillow around her neck to literally block her from being able to reach her face (like how a dog gets a cone at the vet)