Wills generally state that they revoke all previous wills, so generally, yes, new will take precedence over older ones, usually. If your mother has an existing will that she wishes to update, she can do that by executing a new will or executing a codicil (a document that changes simple terms in an existing will without revoking the existing will). The trick is making sure she complies with whatever requirements exist in her state to properly execute a will. For instance, in Indiana, a will does not need to be notarized, but it does need to be witnessed properly by two neutral witnesses.
Answered on Feb 20th, 2012 at 3:51 PM