Clarify overlap in LPA and AMD

An Advance Medical Directive (AMD) informs a person's doctor that he does not want the use of any life-sustaining treatment in the event that he becomes terminally ill and unconscious, and where death is imminent.

On the other hand, a Lasting Power of Attorney (LPA) allows a person to appoint one or more people (donees) to make decisions for him if he should lose mental capacity.

This includes giving or refusing consent to the carrying out or continuation of healthcare treatment.

This gives rise to a potential overlap between an LPA and an AMD.

If a person has signed an AMD, and then subsequently signs an LPA authorising a donee to make decisions on his healthcare treatment, would this override the existing AMD?

Ng Wei Shee