SDCL § 15-6-5(c): Service on numerous defendants.

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