Maryland Code, Estates and Trusts § 13-219

(a) In the absence of actual knowledge or of reasonable cause to inquire whether the guardian is improperly exercising the guardian's power, a person dealing with the guardian need not inquire whether the guardian is exercising it properly, and is protected as if the guardian properly exercised the power, except that every person is charged with actual knowledge of any limitations endorsed on the letters of guardianship.

(b) A person need not see to the proper application of estate assets paid or delivered to a guardian.