Before Chicago Peter was a member of another Chicago group called The Exceptions.
Only discovered them through an internet station and never heard them on the radio.
I don't know if it would be unacceptable to post another band other that Chicago but here's a couple of songs by them.
The 1st has Pete on lead and don't know that name of the other guy.
This other one may sound a bit like Chicago, some may disagree.
It's the same group inspite no S at the end.