Credit: John M. Heller/Getty Images; Todd Williamson/FilmMagic

Mackenzie Phillips — who has admitted to having a decade-long sexual relationship with her father, 60s musician John Phillips — is returning to The Oprah Winfrey how.

Joining her?

Her half-sister Chynna.

Mackenzie will appear via satellite on Friday; Chynna will be live in the studio, has confirmed.

Still no word on whether the two will interact.

On Wednesday's show, Mackenzie opened up about her affair with her father. She said she became pregnant and didn't know who had fathered the child. So she had an abortion, which her father paid for, "and I never let him touch me again."

In the new Us Weekly (on newsstands now), Chynna gives her side of her sister's sad story.

She says the news sent her into "a deep, deep sadness and depression for about 10 days. A part of me died when I found out."