How do you get the one sister you have to help?

You're going to have to separate the inheritance out of the equation. No doubt your folks wanted everything split evenly between the two of you, so don't go there.
Once you take the money aspect out of it, then quit trying to MAKE her responsible. Sorry, it's not fair and a stinkin' bummer, but some people are just NOT going to step up to the plate. You can't cajole them, guilt them or whatever you had in mind. It is what it is. Doesn't mean it's right, just a fact. Do for your mom because you know it's what is important to you, forget the rest.

I have to agree with Nancy. From experience and from reading many posts on this site, it is virtually impossible to in some way "get" a sibling to care and take part, especially one that never has before. I did have some luck when I told my sister who lives 3,000 miles away if she could at least call my mother and take some of the burden off me as I do and have always done everything for my parents, even when my sister lived closer. I was having serious problems with my mother and needed her help; she finally does call my mother; but was very reluctant to do so as she said she has to prepare herself emotionally to even call. Well, so do I, but that is nothing compared to all the other things I have and have had to do. To top it off, my mother thinks my sister has a heart of gold. Funny, actually as they never, ever got along. And I feel like telling my mother that "the heart of gold" said she is never coming back this way even if my mother passes away. So, that just adds insult to injury when you get stuck with all the work and get no credit, just complaints. This is because I was always the easy one, the one who would never say no. But, strange, the one who hurt you over and over, is the one that gets praise.

I have figured out that we do all the work and also get all the blame for what they are not happy for in their lives. But, the one who does nothing or virtually nothing, is well thought of....interesting. Good luck and just continuing doing the right thing, that is what I do; and I willnever change. Take care.

Sibling relationships can get very difficult in caregiving situations. The Visiting Nurse Service of New York has a nice article about seeing all sides of the situation:

Your sister is gonna do what your sister is gonna do. Maybe she has good and sufficient reasons for her behavior. Maybe she is a selfish witch. But you are unlikely to be able to change her. It might help to ask for very specific help. Respite care from July 5 through 7, for example. She can still say yes or no, but specific requests are harder to turn down sometimes.

About the money. .. More than likely the estate, if there is anything left, will be split evenly. That how it usually goes. So ... charge for your services NOW. I think when the parent can afford it he or she should be paying their own way all along. This is good for three reasons:
1) There may not be anything leftover after all is said and done. If Mom lives long enough she may need more care than you can provide in a private house. A care center can quickly use up any estate and Mom may then require public assistance. For either you or your sister to count on getting money after Mom dies may not be realistic. Why shouldn't she pay you now? What is she saving it for -- her old age?

2. If the caregiving child gets paid along the way, then the issue of unfairness of the will goes away. They are two separate issues. Treat them as such.

3. The caregiver incurrs the expenses along the way. For many, the out-of-pocket expenses can be substantial and getting some reimbursement now allows the caregiver to be more responsible in planning for her own future and meeting other family needs.

My recommendation is to have a care agreemen drawn up to address payment now, encourage your sister's help, but mostly resign yourself to acting like an only child, and let the will play out as it may.

My 92-y-o mother has severe arthritis and mild cognitive impairment. She is now living indpendently in subsidized housing. She has no assets and a very small SS check. If she becomes unable to live alone and one of my sibs can take her in, I would expect them to get at least the postion of her check that is now going to her housing, and that every expense they pay for her would come out of that small check. It is only fair and sensible. Why should they take care of her financially so that her small checks can be saved to split among the other siblings? That makes no sense at all. Fortunately all 7 of us are on the same page about that!

If your sister objects to your mother paying you for her room and board and care, too bad so sad. It is still the right thing to do.

Great answer, Jeanne - just yet another of your insightful and helpful answers!