Sec. 4. Any person interested as or through an executor, administrator, trustee, guardian, or other fiduciary, creditor, devisee, legatee, heir, next of kin, or cestui que trust in the administration of a trust, or of the estate of a decedent, a person under eighteen (18) years of age, or a mentally incompetent person may have a declaration of rights or legal relations:
(1) to ascertain any class of creditors, devisee, legatees, heirs, next of kin, or others;
(2) to direct the executors, administrators, or trustees to do or abstain from doing any particular act in their fiduciary capacity; or
(3) to determine any question arising in the administration of the estate or trust, including questions of construction of wills and other writings.