ROCHESTER — Black Swan Living paid a combined $11.85 million for two Rochester housing complexes in April to grow its portfolio of Minnesota housing to almost 2,400 units. Black Swan, a Rochester-based housing investment group led by Nick and Dr. Elaine Stageberg, purchased the West Willow Apartment Homes at 1901 26th Ave. NW and The Quarters at Rochester student housing apartments at 826 21st Ave SE. in two separate deals. On April 23, Black Sw…