735 ILCS 5/4-212
Any person having a lien upon or any interest in the water craft attached, may intervene to protect such interest, by filing a petition, entitled an intervening petition; and any person interested may be made a defendant at his or her request, or that of any party to the action, and may defend any petition by filing an answer as hereinafter provided, and giving security, satisfactory to the court, to pay any costs arising from such defense; and upon the filing of any intervening petition, a summons, as hereinbefore provided, shall issue; and if the same shall be returned not served, notice by publication may be given as hereinabove stated and several intervening petitioners may be united with each other, or the original, in one notice.
735 ILCS 5/4-212