There are several challenges to researching individual musicians and the bands in which they played.
As family stories are verbally handed down, dates and details can be lost or changed. It's very difficult to confirm that someone "sat in" with someone else. Occasionally confirmation appears in musician memoirs, oral histories, or even in a photo or newspaper account. In many cases, examining the birth and death dates and life histories of the two people involved show that they were never in the same city at the same time, or that one was an infant or not yet born (or had died long since) when the other was performing. The more details that drop out of the story as it is handed down, the harder it is to confirm that it happened.
Sometimes birth, marriage, and death certificates were destroyed in courthouse fires. In these cases, census records can help determine a musician's location within a ten year period. If the state and county of any of the certificates is known, it may be possible to get copies from the County Clerk's office. Under the Libraries and Archives tab in the toolbar above are Chicago repositories that have materials related to Chicago jazz. Some of those repositories, such as the Chicago Public Library and the Newberry Library, may have genealogical resources.
Searching newspapers may or may not reveal the names of band members. Feature articles and photos are more likely to list personnel than club advertisements, which often list only the bandleader's name. If the band or bandleader's name is known, it may be possible to find performer information from contracts by using the Musicians Union files at Chicago Public Library. Names can also change over time, early spellings may not be the same as what's used now. It's important to try to track as many variations as possible -- ask older relatives about spellings of names, ask to see family Bibles and family trees. Newspapers also misspell names, so it's important to think creatively when searching for musician info there.
The sources on this page will help researchers get started. The Writing a Course Paper? tab covers several important Chicago musicians and groups, but the page also contains resources useful for family research.