It all sounds very sad and worrying, but being totally honest, if both your sister and her husband “claim” they are fine, maybe they just don’t want your help.
You could contact social services yourself again and simply tell them your concerns, in theory they should follow this up, in practice who knows!
Does she not have any kind of MS specialist?
I think you’ve done your very best and you and your other sister might just have to leave them to it, however much this doesn’t sit well with you, you’ve done your best.
Do they have any children or close friends?
Churchill to be axed from British banknotes in the name of diversity.

