Mich. Comp. Laws § 600.1973

Sec. 1973. In any action in which there are unusually large numbers of parties on the same side, the court upon motion or of its own initiative may order that service of their pleadings and replies thereto need not be made as between them, and that any cross claim, counterclaim, or matter constituting an avoidance or affirmative defense in such pleadings shall be deemed to be denied or avoided by the parties not served, and that the filing of any such pleading and service thereof upon an adverse party constitutes due notice of it to all parties. A copy of every such order shall be served upon all parties in such manner and form as the court directs.