I hate to sound cynical but the odds of someone co-writing the next big hit and your collaborator stealing the song and making the big money...well, I'm guessing that is probably about the same odds as winning the lottery.

What is more likely is you'll turn people off if you whip out your homemade contract and bug everyone to fill in all the blanks every time you sit down in a creative session.

Maybe a better approach would be to 1) work with people you trust and 2) record the sessions and keep those recordings in case something were to really take off. That way you don't have to fool with contracts for the 99.999% of songs that won't go anywhere but you'll be prepared if a good one appears.

Just my thoughts.