Extra Music Tracks For Genesis?

I have a question about the viability of a particular project I'd like to work on.  It's something that I'd like to apply to a lot of games.

Basically, imagine a game like Sonic The Hedgehog, where all 3 acts of each 'zone' are the same music. Would it be possible to modify a rom to look for additional tracks so every single level can use different music?

Original Sonic 1 has roughly 15 songs. My idea would increase that by 12. Is it just a matter of changing some simple data to reference an extra audio track # on the 'virtual CD' that it's referencing? Or is there something in the coding of the game where that would take substantial effort?

I have a lot of ideas on how to use that and would look to do this for a ton of games if I can find a partner to help me. I am still learning but I have both the time and the motivation, which would include editing the audio to the correct format/length (proper looping, etc.).