My friend and I are starting up a business to sell an invention. We signed a partner agreement, and will be registering as a business at some point. I have another friend that is helping us do a specific part of the design and manufacturing. That is the only aspect of the business he is working on. We are going to pay him an initial cash payment and then give him a percentage of profit for a certain number of years. I'm not sure if I should consider him a partner, an employee, a contractor etc. It seems like he would be closest to a partner, but he is only working on a small portion of the entire business.
Any input would be great.