735 ILCS 5/12-139: Redemption by joint owner.

Except as to any sale had by virtue of a judgment of foreclosure in accordance with Article XV of this Code, any joint owner, his or her heirs, executors, administrators or assigns, or a judgment creditor of such joint owner, may redeem the interest of such joint owner in the premises sold under judgment, in the manner and upon the conditions hereinbefore provided, upon the payment of his or her proportion of the amount which would be necessary to redeem the whole.