The owners of a combined 3.29-acre parcel fronting Maple and Park Streets downtown are seeking to replace four apartment buildings there with new structures that will roughly triple the number of units available while putting nearly all parking underground. Commonly known as ‘Merritt Apartments,’ the apartment buildings rise as high as three stories and currently include 38 units that offer no elevators and limited handicapped accessibility, according to an application filed June 1 on behalf of M2 Partners LLC. Plans call for four 4-floor multi-family dwellings that will include 60 condominium/townhouse and 62 midrise apartment units, according to the application, filed by attorney Steve Finn of Stamford-based Wofsey Rosen Kweskin & Kuriansky LLP. Composed of townhouse-style structures that meet New Canaan’s aesthetic by using stone, clapboard and shingles, the development “will help to maintain the vibrancy and economy of the downtown area by replacing outdated buildings with a beautiful new complex designed to look like townhouses with distinct and individual elements,” Finn said in a summary attached to a special permit application. “Increasing density will provide retailers with more people living within easy walking distance to downtown providing needed patronage for local stores, shops, restaurants and the movie theater.