Maryland Estates and Trusts Section 5-207

      (a)      Regardless of whether a petition for probate has been filed, a verified petition to caveat a will may be filed at any time prior to the expiration of six months following the first appointment of a personal representative under a will, even if there be a subsequent judicial probate or appointment of a personal representative. If a different will is offered subsequently for probate, a petition to caveat the later offered will may be filed at a time within the later to occur of:

            (1)      Three months after the later probate; or

            (2)      Six months after the first appointment of a personal representative of a probated will.

      (b)      If the petition to caveat is filed before the filing of a petition for probate, or after administrative probate, it has the effect of a request for judicial probate. If filed after judicial probate the matter shall be reopened and a new proceeding held as if only administrative probate had previously been determined. In either case the provisions of Subtitle 4 of this title apply.