State conservancy rules prohibited expanding the footprint of the house because it would mean encroaching on the 300-foot border next to the Alexauken Creek.
"I wouldn't consider selling the house and moving," Joanne says. "For years, my parents lived a few miles away, and Laura and I ran a shop called Designing Women until my sister was injured and my mother and I ran the shop alone."
Her parents' home had long been a center for visits from out-of-town relatives, Joanne says: "We are a family that is very close, and it is important to have a center place where everyone can get together."
Her house, now that center place, had only the two bedrooms, however, and leaky insulation, as well.
When Joanne complained about the challenges that a renovation would present, sister Lois, who lives in London, reminded her of Brett Webber, the Philadelphia architect whose mother had worked with the Blasenheims at their clothing store.
The solution to her building problems, Webber said, was going up, not out.
His design filled in the space between the second-floor bedrooms and the roof of a single-story living room with a studio and a guest-bedroom area of about 800 square feet.
Included, too, was space for an elevator between the kitchen/dining room and the living room.
The new studio/guest-bedroom wing sits atop the first-floor porch, and it's hard to discern the house's split-level heritage. But it retains its original footprint, and does not encroach on the protected creek area.
Doors, windows, and other features were installed with universal design in mind: wider doorways and lower light switches to facilitate mobility for Laura.
The main entrance was moved from the dining room to the kitchen, and a small porch was added to the original entrance.
"The house became LEED certified," Webber says, referring to Leadership in Energy and Environmental Design, "and we did simple things to make it go green."
Larger windows and sliding doors in the living room invite sunlight to enter.
"The sticker shock of what they needed was offset by the 30 percent savings in fuel and electricity," Webber says.
The kitchen and dining room form one bright space, with five-foot windowsills bedecked with collections of china and shining glassware. On a recent summer day, the long table was set for a meal with blue placemats. (The London contingent of the family was visiting.)
A four-by-five-foot opening in the wall near the staircase brings even more light from the living room to the dining area.
Between the rooms, the open door to the tiny elevator reveals photos depicting years of family history: friends and relations at weddings and parties; young soldiers in uniform; everyone smiling from frames of various sizes and materials.
"It is important for Laura to know that she is not alone, and that she has a huge family of people who care about her," says Joanne, pointing to the images in the elevator.
Up on the second floor, the sisters' new studio is filled with light and with Laura's paintings of flowers and landscapes. A line of sewing machines fills one wall.
Joanne, an art-school graduate, began designing doll clothes and moved on to designing clothing for women. With her store closed, these days she designs for private customers.
"We love the house now," Joanne says. "It is so easy to live here, and we have the studio and the bedroom behind it for guests and the assurance that Laura can freely have access to the entire house and not be confined to one area."