Revenue share format is a very popular method of working in the indie game development scene. This format is basically people forming a group and develop a game without any payment until a demo or the game itself is released. Usually this groups are not legally established as companies until the release of the game or if they get funds.
Is there any type of document that could be used to protect someone's work in this type of scenarios? For example, a document that is signed by everyone on the group that explicitly describes what the distribution of work, which could be used if it is needed later on as a proof in any legal scenario?