(750 ILCS 5/512) (from Ch. 40, par. 512)
    Sec. 512. Post-Judgment Venue. After 30 days from the entry of a judgment of dissolution of marriage or legal separation or the last modification thereof, any further proceedings to enforce or modify the judgment shall be as follows:
        (a) If the respondent does not then reside within this State, further proceedings shall
    
be had either in the judicial circuit wherein the moving party resides or where the judgment was entered or last modified.
        (b) If one or both of the parties then resides in the judicial circuit wherein the
    
judgment was entered or last modified, further proceedings shall be had in the judicial circuit that last exercised jurisdiction in the matter; provided, however, that the court may in its discretion, transfer matters involving a change in the allocation of parental responsibility to the judicial circuit where the minor or dependent child resides.
        (c) If neither party then resides in the judicial circuit wherein the judgment was
    
entered or last modified, further proceedings shall be had in that circuit or in the judicial circuit wherein either party resides; provided, however, that the court may, in its discretion, transfer matters involving a change in the allocation of parental responsibility to the judicial circuit where the minor or dependent child resides.
        (d) Objection to venue is waived if not made within such time as the respondent's answer
    
is due. Counter relief shall be heard and determined by the court hearing any matter already pending.
(Source: P.A. 99-90, eff. 1-1-16.)