A petition under section 30-3415 or 30-3421 may be filed by any of the following:

(1) The principal;

(2) The attorney in fact;

(3) The spouse, parent, sibling, or adult child of the principal;

(4) A close adult friend of the principal;

(5) The guardian of the principal;

(6) The attending physician or other health care provider; or

(7) Any other interested party.