[dirktheman]

Be upfront. Tell him you like the idea, but you don't like to feed another three mouths who bring nothing to the table. Tell him you want to continue working on the idea, and make clear terms what he will do regarding getting users and doing bizdev. Don't split it 30/70 (since you're doing all the work now) but rather keep it 50/50 to eliminate friction.

[akg_67]

I second this idea. Just talk to the other three mouths. Ask them what they are bringing to the table, what their contribution will be, how they will add value and how they should be compensated.