Md. Code, Courts and Judicial Proceedings § 3-408

Any person interested as or through a personal representative, trustee, guardian or other fiduciary, creditor, devisee, legatee, heir, next of kin, or beneficiary of a trust, in the administration of a trust, or of the estate of a decedent, a minor, a disabled person, or an insolvent, may have a declaration of rights or legal relations in respect to the trust or the estate of the decedent, minor, disabled person, or insolvent in order to:

(1) Ascertain any class of creditors, devisees, legatees, heirs, next of kin, or others;

(2) Direct the personal representative, guardian, or other fiduciary or trustees to do or abstain from doing any particular act in their fiduciary capacity; or

(3) Determine any question arising in the administration of the estate or trust, including questions of construction of wills and other writings.