William and Margaret Kienast recently received a letter from a Rock-ford, Ill. woman they had never met. Inside was a check for $10 and a note that said, in part, "This is to let you know that people still care."

Mail from strangers is no novelty for the Kienasts. The birth of their quintuplets, Amy, Abigail, Sara, Ted and Gordon, 13 years ago this Feb. 24 was reported around the world and resulted in hundreds of telegrams, letters and gifts to the happy if harried parents.

But the couple are gaining notoriety for a much less pleasant reason these days. The bank that holds the mortgage (at 7.5 percent) on their 14-room home in Liberty Corner, N.J. announced last month its decision to foreclose on the property on Valentine's Day and sell it at public auction. (The house and four-acre tract would probably bring $300,000.) The Kienasts—whose other children, Meg, 16, and John, 14, were, like the quints, conceived with the help of fertility drugs—haven't made a mortgage payment in more than four years. They reportedly owe the Crestmont Federal Savings and Loan Association office in Westfield, N.J. in excess of $50,000. Since publicity over the foreclosure broke a few weeks ago, Bill Kienast has worked out an arrangement with the bank to forestall the loss of his home, but even so, he admits, "Right now things are pretty much hand-to-mouth."

Bill and Peggy Jo Kienast's lives have been a heady series of contrasts since the arrival of their children. Back then, their monthly mortgage payment was just $107—and members of a nearby homebuilders' association offered their services to finish a two-bedroom addition to the house in time for the quints' arrival home. "We were inundated with offers," Bill, now 51, recalls. The Kienasts signed their kids up to advertise products like Keds sneakers, Hold cough suppressant and Kodak film. But they spurned most commercial advances because, as 43-year-old Peggy Jo puts it, "most of them were outlandish schemes." One man, for example, wanted to set the Kienasts up in the Callander, Ontario home of the famous Dionne quintuplets and, for a fee, allow the public to come and watch them. The Dionne quints were forced to do that from 1934 for a period of seven years—and grew up an unhappy lot. "We don't want to exploit the kids," Bill Kienast told most would-be sponsors.

Still, in 1971 the money they did accept for endorsements enabled Kienast, a former plastics salesman for the Tenneco Company, to buy a division of that firm which manufactured the plastic used in eyeglass frames. For the next few years the Kienasts poured all their earnings, including the quints', into the business. It was a modest success, at one time employing 15 people on round-the-clock shifts. "We were comfortable," recalls Bill. "We had the perks, including a Jaguar, and a lot of the bills were paid through the firm. But we never took a lot out of it monetarily. If they're going to tax it away, why bother?" Now, though, Bill sardonically concedes: "We should have hid the money out in the barn."

The Kienast fortunes took a bad turn in 1977, when cheap frames from the Far East appeared on the market. The family refinanced the mortgage on the house to try to keep the business afloat, but to no avail. In October 1979 the business went bankrupt. "You sit around and think, 'What did I do wrong?' " Bill says today. According to a former business associate, though, Kienast was simply a victim. "It's not that Bill was in a high-growth area and screwed up," says this man. "It was a very competitive shrinking area."

The Kienast children seem unscarred by the family's financial woes. The kids say they have not been teased by schoolmates about their highly public problems—and they all regret that they can't help more with the family budget. They haven't made a commercial since the mid-'70s, though not for lack of interest. "I'd love to do an ad for Häagen-Dazs," says Abigail. "I'd like to do one for The Official Preppy Handbook," counters Amy, who intones in her best Locust Valley lockjaw, "Hi, my name is Muffie."

The family currently is living on the income from Peggy Jo's sporadic real estate sales. Bill has formed a new company, which buys and sells plastics. The Kienasts won't talk about the deal they've made with the bank. "It's something we can work with," says Bill.

No one in the family spends much time looking back. "I don't know what we could have done differently," maintains Bill, who has remained self-employed since the quints' birth. "It never occurred to us that we were throwing good money after bad," adds Peggy Jo. "It seemed if we put it into the business, our business would grow strong and take care of us for the rest of our lives. It just didn't work out that way."