Mass. Gen. Laws ch. 190B § 3-401
A formal testacy proceeding is litigation to determine whether a decedent left a valid will. A formal testacy proceeding may be commenced by an interested person filing a petition as described in section 3-402(a) in which that person requests that the court enter an order probating a will, or a petition to set aside an informal probate of a will or to prevent informal probate of a will which is the subject of a pending petition, or a petition in accordance with section 3-402(b) for an order that the decedent died intestate.
A petition may seek formal probate of a will without regard to whether the same or a conflicting will has been informally probated. A formal testacy proceeding may, but need not, involve a request for appointment of a personal representative.
During the pendency of a formal testacy proceeding, the magistrate shall not act upon any petition for informal probate of any will of the decedent or any petition for informal appointment of a personal representative of the decedent.
Unless a petition in a formal testacy proceeding also requests confirmation of the previous informal appointment, a previously appointed personal representative, after receipt of notice of the commencement of a formal probate proceeding, shall refrain from exercising the power to make any further distribution of the estate during the pendency of the formal proceeding. A petitioner who seeks the appointment of a different personal representative in a formal proceeding also may request an order restraining the acting personal representative from exercising any of the powers of office and requesting the appointment of a special personal representative. In the absence of a request, or if the request is denied, the commencement of a formal proceeding has no effect on the powers and duties of a previously appointed personal representative other than those relating to distribution.
Mass. Gen. Laws ch. 190B, § 3-401