35 ILCS 5/1403
Whenever any proceeding provided by this Act is begun before the Department, either by the Department or by a person subject to this Act, and such person thereafter dies or becomes a person under legal disability before such proceeding is concluded, the legal representative of the deceased or of the person under legal disability shall notify the Department of such death or legal disability. The legal representative, as such, shall then be substituted by the Department for such person. If the legal representative fails to notify the Department of his appointment as such legal representative, the Department may, upon its own motion, substitute such legal representative in the proceeding pending before the Department for the person who died or became under legal disability.
35 ILCS 5/1403