My sister has severe mental health issues, and she cut off the whole family for about seven years many years ago. The family had not done anything to deserve this, and didn’t really have any idea why, but we had to accept it. Eventually, after a severe breakdown, my sister was diagnosed and treated, and after two years of treatment she made peace with the family. My point is that we don’t know how or why Silverlady’s sister has not been in contact. We don’t know who broke off the relationship, or if it drifted gradually until it was no more. Silverlady says it was a difficult relationship. Sometimes it’s easier to let go in a difficult relationship because the constant hurt is too much to bear. The point is that Silverlady now wants to make contact, so she should. If her letter is ignored then she will know where she stands in this relationship, but if her sister replies then it may be possible to restore some part of the relationship.
My own sister is now ill again, and she has gone down the line of almost no contact again, including with her elderly mother and her four adult children, and all her grandchildren. I accept the situation because I have lived through it before, but if I knew my sister was seriously ill I would make contact with her, and she could decide whether to respond or not. She is my sister after all, and whatever happens nothing will change that, or the fact that I still care for her. Maybe Silverlady feels the same.