The musical couple returned to the stage in Italy two weeks after the shocking death of their son's nanny.
Katharine McPhee once again took the stage, alongside her husband, David Foster, for their first live performance since the tragic and shocking death of their son's nanny earlier this month.
McPhee, 39, and Foster, 73, took the stage at a private event in Ravello, Italy, on Tuesday, where they were joined by actor Erich Bergen, who previously starred opposite McPhee in Waitress.
McPhee, Foster and Bergen all wore white for the musical event, with McPhee stunning in a white dress, while Foster played at the piano in an ivory tuxedo.
Bergen -- who starred as Four Seasons singer Bob Gaudio in the 2014 film Jersey Boys -- shared a video of the performance to Instagram on Wednesday, and remarked, "Singing Frankie Valli and The Four Seasons songs in Italy just seems appropriate. So great to perform with my friends @davidfoster @katharinefoster and @thelondonessentials."
Tuesday's appearance in Italy comes two weeks after Yadira Calito -- who worked for the family as a nanny to their 2-year-old son, Rennie Foster -- was the victim of a fatal traffic collision on Aug. 9.
The accident happened when an 84-year-old woman crashed her Toyota RAV4 into the Hamer Toyota dealership service center in Mission Hills, California, causing major damage and colliding with several people inside.
Two employees, ages 23 and 35, were transported to a local hospital with non-life-threatening injuries. Calito, 55, was a customer at the dealership and sustained fatal injuries in the crash. She was pronounced dead at the hospital. The driver was not injured in the collision.
On Aug. 11, McPhee announced she was leaving the couple's Hitman Tour due to a "horrible tragedy." In a message to her fans in Jakarta, Indonesia, she shared on Instagram, "It's with heavy heart I announce I have to miss our final 2 shows of our Asia run." The nature of the tragedy was not specified at the time.
A source recently told ET, "David and Kat are willing to do anything they can for their former nanny's family during this very difficult time.
"They considered their nanny to be part of their family and are devastated by her passing," the source said. "They just want to be there for her loved ones however they can be and support them through this."