Tenn. Code Ann. § 32-1-103: Witnesses - Who may act

(a) Any person competent to be a witness generally in this state may act as attesting witness to a will.

(b) No will is invalidated because attested by an interested witness, but any interested witness shall, unless the will is also attested by two (2) disinterested witnesses, forfeit so much of the provisions therein made for the interested witness as in the aggregate exceeds in value, as of the date of the testator's death, what the interested witness would have received had the testator died intestate.

(c) No attesting witness is interested unless the will gives to the attesting witness some personal and beneficial interest.