The 47-year-old "Black-ish" star is set to appear as singer Grace Davis in the new movie and, speaking to Britain's Daily Mail newspaper, she opened up on the "I'm Coming Out" hitmaker's reaction to her vocal recordings.
While Diana hadn't seen the movie at the time of the conversation, Tracee recalled, "I picked her up and we sat in my car. We were holding hands and crying as the songs played. It was a special moment."
While the star was met with approval from Diana, she confessed she "thought it was unfair I was being asked to sing" over fears she'd be compared to her Motown legend mum.
However, she reflected she found it easy to distance herself from the "Chain Reaction" star in the studio - because Diana always kept her music and family life separate.
"My mom recorded while we were sleeping, so she could be available when we were awake," she said. "So, I didn't get to sit and sleep in a recording studio."
"I knew where the mic was, but I didn't know what the controls were for. For Christ's sake, doesn't someone just press the red button?!" she joked
Tracee performs six numbers in the movie, also starring Dakota Johnson, which is available digitally now.