Catherin

It's highly recommended to sign a shareholders agreement, since the bigginning of the business, when the relationship is good. Quebec legislation has many laws and bylaws to solve conflicts and disputes among shareholders, but they don't take care on your best personal interest! So, prepare a draft together with your shareholders before going to see a lawyer. Think about how to share your profits, your losses, what happen if one of you want to go out of business and what happen if you'll need extra funding...and the most important, how to reach a decision (the voting process) when shareholders and directors of the board have different opinions.

Good luck!