How can I prove that my sister had my father change or add an amendment to a revolocable trust while he was diagnoised with alztimer's yrs ago and has just pass away.
You should consult with an attorney who can review the specific documents. In general, merely being diagnosed with Alzheimer's will not defeat your father's legal capacity to alter or amend a revocable trust. However, depending on the facts and circumstances, she may have used undue influence to take advantage of your father. I offer a free initial consultation if you would like to discuss this further.