I think that a limited partnership is one way that you could structure others putting money into a business, such as friends or family. Limited partnerships are generally reserved for businesses like law firms and CPA firms because they can all share in the profits, but then have a single managing partner in charge of all the day-to-day operations. Savvy investors, like angel investors, likely won’t go for this type of structure because they will want more say in the operations of the business.
We have an article on seller financing, although it doesn’t directly relate to real estate. It should still be helpful for your understanding on how it works to buy a business, and if you want to get seller financing for real estate then the background information is very similar.