@TruHart1, Martin is about the right age for the song in "Night and Day." But, Cole Porter as a heterosexual in the film seemed too close to the way Mary Martin lived her own life. And, at age 67 in the appearance with Merman, Mary likely finally understood the lyrics to "My Heart Belongs to Daddy."
However, Martin was the first life-long Broadway musical performer to receive the Kennedy Center Honors (1989). Merman passed away in 1984 before Kennedy Center could honor her.