Valuing a RE Investment business

[Jake DeBoer]

I'm looking for recommendations on how to value a REI business, specifically how to price a buy-in for an additional partner. Long story short, several years ago there were four of us looking to partner on an opportunity but one partner had to back out. The three remaining partners moved forward with opportunity and invested equal capital (1/3rd each). Since then we've purchased additional properties, made improvements and seen significant appreciation. Now the original forth partner is interested in buying in and becoming equal (or potentially smaller %) partner and I'm struggling on the best way to value that buy in price. Any recommendations?