CBS will run four episodes from the debut season of the UPN drama “Veronica Mars” on Fridays starting July 29. But that does not mean UPN’s highly anticipated Chris Rock autobiographical comedy “Everybody Hates Chris” will move to its sister network CBS if the show is a hit, said UPN President Dawn Ostroff.

“I want to be perfectly clear that UPN is not a farm system for CBS,” Ms. Ostroff said during UPN’s presentation Thursday at the Television Critics Association summer press tour. “We are our own vibrant network.”

Ms. Ostroff was responding to CBS Entertainment President Nina Tassler’s comments at her network’s executive session Tuesday, when she refused to comment on the likelihood that “Chris” might migrate to CBS.

“We got it, we produced it and we are broadcasting it,” Ms. Ostroff said of “Chris.”

Chris Rock is confirmed to narrate throughout the life of the series, she said. “Chris has been involved in the stories, and he’s executive producer of the show,” she added.

She said the four episodes of “Veronica Mars” airing on CBS during the summer represent a “positive way” for the networks to work together. But she added, “The two networks have two separate and individual development pipelines to feed their respective networks.”

The pilot of “Veronica” and a second episode will air on CBS July 29 starting at 8 p.m. (ET). Single episodes will air Aug. 5 and Aug. 12 at 8 p.m.

Ms. Ostroff said lead actor Shannen Doherty is being replaced in UPN’s upcoming fall sitcom “Love, Inc.” because the network wanted “to go in a different direction” with the character. She added that a replacement would be named soon.

Former “America’s Next Top Model” judge Janice Dickinson will return to the show next season for at least some of the episodes. “Janice is going to appear in the show, but in a different way,” Ms. Ostroff said. And in a nod to network cross-promotion, the most recent “Model” winner, Naima Mora, will appear in the first episode of the second season of “Veronica,” Ms. Ostroff announced.

UPN also released its fall premiere dates: