Hi so sorry your wife is suffering like this. Try and encourage her away from the brush. The damage to her skin will make the need to scratch even worse. I use a heavy moisturiser and rub that into my legs when they are itching. I use hydromol ointment to wash and bathe instead of soap. It helps a lot. I also have a strong antihistamine which I take orally.
I’ve changed all my products to one brand and this has helped massively. When I’m flaring I don’t use anything perfumed at all and wear loose cotton clothes. Hope this helps. Good luck and keep sharing