(a) The statutory guardian of an infant or of an individual with mental illness may file or unite in the petition in the names of, and in conjunction with, the infant or person of unsound mind.
(b)
(1) If the petition is filed against infants or individuals with mental illness, the guardian may appear and defend for them and protect their interests.
(2) If the guardian does not, the court shall appoint some discreet person for that purpose.