Parallel assistance merging businesses

I have need of your legal assistances regarding protection in a written contract form. Im in the process of merging my newly established business with an existing business. A contract needs to be written up protecting my assets from any liability the company already potentially already has. Also the terms of our verbally agreed on percentages pertaining how the proceeds (money) for the projects will be distributed and deposited into bank accounts. Many things must be accounted for and addressed. Please have experience in this sort of finance aspects and business management merger methodology.