Usually parents love their children, even if the children grow up to be unlovable adults. In my opinion it would have to have been a very bitter, acrimonious parting of ways that would cause a parent to totally disinherit a child.
I have always thought that each child should be the Will as one never knows if the absent child will return and jumps in to offer to give his/her parents care. If that does happen and the parent(s) pass away and that child is left off the Will, then what? Will the siblings share their inheritance with that child?
Maybe the Will could be written with both scenarios in place, that if that child never returns here is what to happen, and if that child does returns and helps out here is what to happen.
If your parents change the will, have them write something to indicate that it is what they wanted and get it notarized, so that your sister cannot dispute it. Unfortunately, siblings that are oblivious to aging parents, reappear when it is time to collect the inheritance, and most likely your sister will come back into the picture sometime, when it can benefit her financially. My personal opinion is that siblings that don't give their elderly parents the time of day, don't deserve two cents.
Yes, that was my first question too: "taken off the will" by whom?
By the person making the will, if of sound mind, yes, absolutely. By anyone else, absolutely not - no matter how much of a self-centred unfilial rat-bag you might happen to think she is.
I read in your profile that your father has dementia. If he's not cognizant enough to understand the impact of executing a Codicil, it's too late to make any changes.
My concern though is whether this is what you want or what your parents want?
If the existing - even though 20 years old - is valid, mom will need to do a codicil to the old will rather than a new will. Sissy could petition the court to through out the new will & the judge could require an evaluation on the validity of an entirely new will. By doing a codicil to the old will, it recognizes what was in the old and makes changes to it. I'd call the old law office to see if they are holding the original (most do) and have them to the codicil as this will be likely the most cost efficient way. Do whatever you can to get mom looking & acting as competent & cognitive as possible for the appointment too. Good luck.
Maybe the Will could be written with both scenarios in place, that if that child never returns here is what to happen, and if that child does returns and helps out here is what to happen.
By the person making the will, if of sound mind, yes, absolutely. By anyone else, absolutely not - no matter how much of a self-centred unfilial rat-bag you might happen to think she is.
My concern though is whether this is what you want or what your parents want?
Your question sounds as though you are the caregiver and you are the one wanting to remove a sibling's name from your parent(s) will.
You do not have that right.