This is an unofficial version of a Massachusetts General Law.
Section 5-105
(a) Provided that the court has jurisdiction:
(1) venue for a guardianship proceeding for a minor is in the court at the place where the minor resides at the time the proceedings are commenced, or, in the case of a nomination of a guardian by the will of a parent or guardian, in the court of the county in which the will was or could be probated except venue for a guardianship proceeding for a minor in district court or juvenile court shall be in the court where the underlying proceeding was filed;
(2) venue for a guardianship proceeding for an incapacitated person is in the court at the place where the incapacitated person resides or is present at the time the proceedings are commenced, or, in the case of a nomination by the will of a parent or spouse, in the court of the county in which the will was or could be probated. If the incapacitated person has been admitted to a facility referred to in chapter one hundred eleven, section 70E pursuant to an order of a court of competent jurisdiction, venue is also in the county in which that facility is located; and
(3) venue for a protective proceeding is in the court at the place where the person to be protected resides at the time the proceedings are commenced, whether or not a guardian has been appointed in another place or, if the person to be protected does not reside in the commonwealth, in the court at the place where property of the person is located.
(b) If a proceeding under this code is brought in more than one place in the commonwealth, the court at the place in which a proceeding is first brought has the exclusive right to proceed unless that court determines that venue is properly in another court or that the interests of justice otherwise require that the proceeding be transferred.