Actress Mackenzie made the claims in her autobiography High On Arrival and in a recent TV interview.
Michelle, the bandmate and ex-wife of Mamas And The Papas star John, told Showbiz 411: "John was a bad parent, and a drug addict. But [expletive deleted] his daughter? If she thinks it's true, why isn't she with a good psychiatrist on a couch?
"I think it's unconscionable that Oprah would let her do her show. I have every reason to believe it's untrue. Oprah should be more judicious about who she has on her show."
She added: "Mackenzie has a lot of mental illness. She's had a needle stuck up her arm for 35 years. She was arrested for heroin and coke just recently.
"She did Celebrity Rehab and now she writes a book. The whole thing is timed."