When seeking to modify a provision of a will, people often add a codicil instead of drafting a new will. Unless you're very careful, a codicil can actually nullify the very provision you want to change!
A codicil is a legal document that allows you to modify an existing will without revoking it in its entirety. However, it is not legally sufficient for you to hand write a new provision on your existing will!
Under Texas law, codicils must meet the same legal requirements as an original will. It must identify the date you executed the will you are seeking to modify. It must specify what information in the existing will is being changed. It must be notarized and witnessed by two people, and you must include a self-proving affidavit that attests to the validity of the existing will. If your codicil does not meet these requirements, it may be invalidated by a court.
If you plan on making significant changes to your existing will, we recommend drafting a new will that revokes all previous wills. That way, there can be no confusion about your intentions.