Four years ago, Cristina Gitti and Matteo Bologna, the parents of two daughters, decided to divorce. But they parted ways by only a flight of stairs. The couple opted to stay put with their girls in the brownstone they had purchased in 2003 in Fort Greene, Brooklyn, for around $1.4 million.

“We were all living up here,” said Ms. Gitti, 48, a fashion designer and the owner of Matta NY, a clothing company, referring to the top level of their three-unit brownstone. Leia mais.