Sec. 2. As used in this chapter, "declarant" means a qualified person:
(1) who has completed a POST form under section 7(a)(1) of this chapter;
(2) for whom a representative has completed a POST form under section 7(a)(2) of this chapter; or
(3) for whom a proxy has completed a POST form under section 7(a)(3) of this chapter;
and whose treating physician, advanced practice registered nurse, or physician assistant has executed a POST form under section 8 of this chapter.