805 ILCS 215/1003: Proper plaintiff.

A derivative action may be maintained only by a person that is a partner at the time the action is commenced and:

(1) that was a partner when the conduct giving rise to the action occurred; or

(2) whose status as a partner devolved upon the person by operation of law or pursuant to the terms of the partnership agreement from a person that was a partner at the time of the conduct.