Mass. Gen. Laws ch. 53 § 99
If, in a city, nomination papers placing persons in nomination for all the offices to be filled at a caucus in any ward are not filed, the secretary of the city committee shall forthwith notify the chairman or secretary of the committee of such ward, who shall forthwith call a meeting of said committee, which may nominate candidates for all offices for which nomination papers have not been filed, and shall immediately file with the secretary of the city committee nomination papers signed by all the members of the committee who agree to the nominations therein made. In case of disagreement two sets of such nomination papers may be filed. If, at the expiration of two week days after the time at which nomination papers were opened, proper nomination papers have not been filed for all the offices to be filled, or upon any vacancy caused by death or otherwise, except a withdrawal, the chairman and secretary of the city committee may file nomination papers for such offices or vacancies.
Mass. Gen. Laws ch. 53, § 99