A parent or a guardian of a minor or incapacitated person, by a properly executed power of attorney, may delegate to another person, for a period not exceeding six (6) months, or in the case of military personnel serving beyond the territorial limits of the United States for a period not exceeding twelve (12) months, any of the parent’s or guardian’s powers regarding care, custody, or property of the minor or ward including, but not limited to, powers for medical care and educational care of the minor or ward, except the parent’s or guardian’s power to consent to marriage or adoption of a minor or ward. The delegation for a minor to a grandparent of the minor, or to a sibling of the minor, or to a sibling of either parent of the minor, shall continue in effect until the time period, or date, or condition set forth in the power of attorney for automatic expiration of the power of attorney occurs. If the power of attorney does not provide a time period, or date, or condition for automatic expiration of the power, the power of attorney shall continue in effect for a period of three (3) years. The power may be revoked prior to the expiration of the three (3) year period, or prior to the time period, or date, or condition for automatic expiration, in a writing delivered to the grandparent or sibling by the delegating parent or guardian. The power of attorney does not need to be notarized or recorded to be valid. However, if the power is recorded, any revocation of the power by a writing must also be recorded before the revocation is effective.