I am developing apps on my sparetime. I am the sole developer, and two non-programmer friends of mine provide vision, content, algorithms and ideas. We always agree happily on all the features, todos and prioritizations. But naturally, coding it is the biggest part.

When selling, we agree on splitting profit equally, that is 33% each.

But version 1.0 naturally does not sell much. And I go on to try to make the app more viral. This includes tons of stuff where the others are of little help. Examples: Adding support for sharing, facebook connect, gameifying, letting users add content, home page, support, maintenance, server services to make it easier for to update content. The list is long. Suddenly I will be doing 100% of a lot of work but only "own" a third of the income.

My friends may either "fade out" of the project after 1.0, or they continue to contribute, but with less value and I would rather exchange them for more programmers or graphic designers. The effort they made to version 1.0 is worth a lot to the app and I realize I would have never done it without them. But I am doing all the work in the end. It is hard to negotiate about splitting 90, 5, 5 instead of 33% each, because the idea is still theirs.

How to solve this? What are the best practices to regard the ownership of the app? What kind of agreements could I make that make it beneficial and motivational for me to continue developing the app?