Md. R. Estate Settlem. 6-151
Promptly after learning of the decedent's death, the custodian of a document appearing to be the last will of the decedent shall file it with the register even if it is not to be offered for probate. The will shall be filed in the county in which administration should be had pursuant to Rule 6-111. A prior will need not be filed with the register unless (a) the custodian learns that the subsequent will has been declared invalid or is being or may be contested, (b) the custodian is requested to produce it in connection with a proceeding to interpret the subsequent will, or (c) the court orders the custodian to produce it. A will to be offered for probate, unless previously filed, shall be filed in conjunction with the filing of a petition for administrative or judicial probate or administration of a small estate.
Md. R. Estate Settlem. 6-151
Code, Estates and Trusts Article, §§ 4-102, and 4-203.