To have a comprehensive Advance Directive in South Carolina, you must fill out two separate forms: a Living Will titled "Declaration of Desire for a Natural Death" and a "Healthcare Power of Attorney" (a.k.a. Health Care Proxy).

Information Required for a Last Will and Testament:
The signatures of both you AND two (2) witnesses must be notarized for your South Carolina living will to be declared valid.
Witnesses CAN NOT be:

• As a spouse, lineal ancestor, descendant of the declarant's parents, or spouse of any of them, you must be related to the declarant by blood, marriage, or adoption.
• Directly accountable for the declarant's medical expenses, and not entitled to any amount of the declarant's inheritance upon his death, whether under a will or as an heir via intestate succession.
• The beneficiary of the policyholder's life insurance.
• Neither the declarant's attending physician nor a member of the attending physician's staff
• A person with a valid claim against the estate of the decedent of the declarant.
• No more than one (1) witness may be an employee of the healthcare facility where the declarant resides. At least one (1) witness must be an ombudsman recognized by the State Ombudsman, Office of the Governor, if the declarant is a resident of a hospital or nursing care facility at the time this Declaration is executed.

Required Data for Naming a Health Care Proxy:
For your SC Advance Directive to be legitimate, BOTH your signature AND the signatures of two (2) witnesses must be notarized. These people CANNOT serve as witnesses:

• Your Spouse, Children, Grandchildren, OR Other Lineal Descendants, for example: Your Parents, Grandparents, Direct Ancestors, Siblings, and their direct descendants or spouses.
• A person who is directly accountable for paying for your medical expenses.
• A person who is specified in your Will or, if you do not have a Will, would inherit your property under Intestate Succession.
• A recipient of a life insurance policy on your life.
• The individuals identified under your Health Care Power of Attorney (also known as a Health Care Proxy) as your agent or successor agent.
• Physician or staff member of your Physician
• Any Person has a legitimate claim to your estate (persons whom you owe money)

(Via Official Site of South Carolina)