The family behind the shuttered Erica's American Diner in Fairfax is working on opening a smaller version of their popular eatery called Erica's Village Diner in Cambridge this April. Linda and Ron Frey — who also own Cambridge Village Market and Milton's Uncle Ronnie's Deli and Convenience and the Frey Family Deli and Convenience Store — opened the original Erica's in Fairfax in 2015 with their daughter, Erica Hayes. Ron Frey, 57, said the couple were obliged to close the diner in July when they lost their lease. Then came a surprise opportunity to buy a building in Cambridge, at 51 South Main Street, in which to open a new version of the diner, Frey said. Erica's Village Diner will have about 35 seats, a third the count of the Fairfax location. While that restaurant served three meals, the new one will offer daily breakfast and lunch. Frey said septic capacity is the limiting factor. Frey, who is also a sugar maker, said the new Erica's will serve about 80 percent of the original menu, including "the world's greatest breakfast sandwich," which features sausage, eggs, cheese and a lashing of maple syrup on a slightly sweet telera-style roll. Follow Erica's Village Diner on Facebook for updates…