Any person interested as or through a personal representative, 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, an infant, mentally incapacitated person, or insolvent may have a declaration of rights or legal relations in respect thereto:

1. (1) To ascertain any class of creditors, devisees, legatees, heirs, next of kin or others; or
2. (2) To direct the personal representatives or trustees to do or abstain from doing any particular act in their fiduciary capacity; or
3. (3) To determine any question arising in the administration of the estate or trust, including questions of construction of wills and other writings.

(RSMo 1939 § 1129, A.L. 1983 S.B. 44 & 45)