BooksnBeer (great name!) - are the sisters estranged? There does seem to be some sibling rivalry there, and I am not sure if it ever goes away in many families.
I have just come out of a three year estrangement with my eldest DD, different reasons, but massively painful, so I understand exactly how you feel. I thought of cutting her out of my will and discussed it with DH, but I don't think I really meant it. DH was certainly against it. I agree with the previous poster who said that it is the last powerful message which you send to your child. She would be devastated, I am sure, if you did this - you would mess up the rest of her life and poison the whole family not only for this generation but for future generations. Is this what you really want? You must feel very bitter, as well as hurt, if you do. And why are you punishing your granddaughters? Surely, if you are staring death in the face, you want to be reconciled with your loved ones? I assume you do love DD or you would not be so hurt. Does she really not know how ill you are? Are you afraid that she would turn her back on you if she did know? Is there anyone who could speak to her/mediate?
Of course, you have a right to do what you wish, but I would urge you to reconsider very carefully. I am not generally one to recommend counselling but, in your case, do you think it might help, as you have an awful lot to contend with at present?
Whatever you decide, I send you hugs and