i've never been sure really - i have one, but as i'm reasonably young, it was made with the intention that should somthing catastrophic happen, my husband/family would at least have some idea about my thoughts and wishes. However, in your position, i might not bother, Don't forget that any decision made is made in hte person's best interests anyway which quite often accord with what people want. Unless she wants something out of the ordinary to happen re care and welfare, i wouldn't bother