Legal Question in Business Law in California

Without more facts, perhaps including those relating to your decision to leave the company, no lawyer is going to be able to draw you a clear road map as to how strong a claim you may have, or how to enforce it. Perhaps the strongest approach would be to assert that a partnership was created between the family company and you, and that you are entitled to withdraw and claim a share of the partnership's valuation under the California Revised Uniform Partnership Act.

On the other hand, the family business may argue that you were only a contractor who agreed to be paid if and only if you eventually delivered a marketable product,

In any event, the reasons for your decision to leave the company may play a paramount role in determining your status and your rights. If you were forced out, you'd be looked upon as a victim; if you decided to pursue greener pastures, you'd be a deserter. What really happened?

Generally speaking, if you are an employee and your job included creating computer code, then the employer owns the copyright on the code and can exploit it as they wish. If you are an independent contractor creating computer code, then you own the copyright and it can only be transferred to the company in writing. If this is a partnership of four people and each of you gets 1/4 of the company profits, then you might be able to enforce that in court.

Especially because you don't already have a written agreement, it would be better for you to make a written agreement with the company as to the terms of your leaving and specify any ongoing royalties you are to receive.