The couple wed in an intimate ceremony at the Church of Saint Yeghiche in South Kensington, London last June (19), and recently celebrated its first anniversary together.
While much has been made of David, 70, and Katharine's 34-year age difference, the hit record producer's daughters Sara, Erin and Jordan have no problem with their relationship - except for "how hot she is."
"Her body is insane," Erin, 37, told People. "When she comes over for family Sundays, I'm like, 'Do not get in a bikini.' My husband's always like, 'Kat, get in the pool!' And I'm like, 'Simon...' "
During their family Sundays - a new tradition that started up when the coronavirus lockdown began - Sara, 39, revealed all of their husbands "hang on the side ogling her."
"Even my 2-year-old son (Otto)," Jordan, 34, laughed.
Joking aside, the three agreed that the age gap had been a positive thing, as it has "really pushed (David) to open up" about his feelings, with Erin explaining, "Our dad comes from a generation where women are more passive. He is also passive about his feelings."
"Kat has really pushed him to open up. We could get into a fight, and then Kat's like, 'No, you have to pick up the phone, call your daughter back.' She's a facilitator, which is really important. She pushes him to be more emotional and more vulnerable."
Jordan also noted that her dad had "been with age-appropriate women forever" before Katharine, adding it "hasn't worked in the past" due to his failed marriages to Linda Thompson, Rebecca McCurdy, B.J. Cook, and model Yolanda Hadid, who he divorced in October 2017.