Help! How do I change a contractor on existing permit?

[Amir Haq]

Hello Chicago area investors/architects/GCs!  I need to change the plumber on my rehab permit for a 3 flat.  I'm ready for an inspection but am using another plumber.  My architect said I have to go downtown and submit paperwork, but others are telling me it can be done online.  I've searched for instructions, asked various people, and no one has a concrete answer- hopefully someone here can help?