For the past 19 years, the Isacs family has hosted Thanksgiving dinner at their home in the Litchfield Hills of Connecticut. Each year, anywhere from 8 to 20 extended family and friends swelled the ranks of the family of four: Peter and Nadine, the consummate host and hostess, and their sons PK, 27, and Christopher, 25. “It has always been our favorite holiday,” said Christopher, because “it’s really just focused on family, along with the concept of gratitude, which has always been very important to us.” Last year, however, they were bracing for a very different holiday. Peter had suddenly passed away in his sleep in late August. “We not only had Peter’s empty seat,” Nadine said, “but other family members who had been celebrating with us for years could not come because of the pandemic—and we were very aware that that was the case for so many other Americans. …