Does a codicil with changes written on it have to be notarized and have witenesses in TN?

Dear Tennessee, As a disclaimer, I practice in Illinois; however, the rules for wills are somewhat universal.    In IL the law regarding the effects of alterations (changes) to wills in summary states that any addition to a will or an alteration, substitution, interlineation or deletion of any part of a will which isn't a revocation of the ENTIRE will is of NO EFFECT, UNLESS it was made by the testator (your mom herein) or by some person in the testator's presence AND by her (your mom herein) direction and consent and unless the will is THEREAFTER SIGNED AND ATTESTED IN THE SAME MANNER REQUIRED TO EXECUTE A WILL.  So UNLESS the changes your mom made were a COMPLETE revocation  of the ENTIRE codicil they are ineffective.  Any partial changes really should have been made as an additional (or new) codicil executed with the same formalities required..witnesses and notarization.    With that said, I advise you to consult with a local attorney to verify that the above is consistent with the laws of Tennessee.  Best wishes to you.