Moms home is not fully paid for. my sister is power of attorney and my brother second power. can my sister give the house to my brother? or sell it to him and not consider me being the third child's need's? or the need's of mom's grandchild who lived with mom from infancy and now 20 year's old?
As your mother's POA and second POA, your sister and brother are responsible for using your mother's property to support her care to the best of their ability. If that means selling the house 1. to pay off the mortgage and 2. to use the remaining money to pay for her care in a facility or a smaller property, so be it. And there is nothing wrong with your brother's buying the house at a fair market price. DebraLee, Igloo and GA's advice explains this part well.
If you and the grandchild are able-bodied, competent adults with no special needs, and you are not your mother's dependants, then there is no reason at all why your sister and brother should take you into account. What were you expecting them to do?
As long as there is a mortgage, ain't nothing gonna happen to sell, transfer or gift the property to anybody till the mortgage is paid in full and cancelled. Most mortgage companies will not just to a transfer of ownership either, the new owner will have to likely get a new mortgage for this (and qualify for it too) unless they can pay in full in cash for whatever the balance is on the note.
Mortgage company doesn't give a ant's butt who pays the note either. If you all don't pay it, the house will go into foreclosure.
If your mom lives in this house, what are your sister and brother's plans for your mom? Are they expecting to take over her care? As I understand, she has some dementia, so this house is apparently still her home? Or is she in a facility? If so, who lives in the house?
The lender can and likely would put pressure on your brother to assume the mortgage, subject to their approval of his credit. Or as Igloo states, your brother would have to get a loan to pay off the existing mortgage.
The lender would also generally have to approve any transfer of title to other than the borrower. Otherwise, it can declare an event of default and accelerate the indebtedness. When I worked in commercial finance, these were standard loan terms.
What this means in layman's terms is that the lender can call the loan and the entire amount can be deemed due and payable... NOW ... within a few months or so as dictated by the lender. If this happens and your brother can't comeo up with enough to pay off the remaining indebtedness, the lender can foreclose the loan.
As to the interest of you and/or the grandchild, if your mother wanted to make arrangements for you and the grandchild, that would be accomplished through a will or trust, over which your sister has no jursidction or power.
As DebraLee writes, if the house is sold, the funds need to be allocated for your mother's care.