When a guardian ad litem is appointed by the court, the guardian ad litem must be appointed as follows:
1. When the infant is plaintiff, upon the application of the infant if the infant be of the age of 14 years, or, if under that age, upon the application of a relative or friend of the infant.
2. When the infant is defendant, upon the application of the infant if the infant be of the age of 14 years and apply within 10 days after the service of the summons, or, if under that age or if the infant neglect to so apply, then upon the application of a relative or friend of the infant, or any other party to the action.
3. When a person with a significant mental illness or an incompetent person is a party to an action or proceeding, upon the application of a relative or friend of such person with a significant mental illness or incompetent person, or of any other party to the action or proceeding.