The cast of "Real Housewives of Beverly Hills" is undergoing a change, and a key cast member has threatened to quit the series if her former husband's fiancée is asked to become a series regular.

Yolanda Foster is said to be miffed that Bravo is considering asking her ex-husband Mohammed Hadid's new fiancée Shiva Safai to become a series regular, especially as Foster is believed to be not too fond of Safai.

"Yolanda is very insecure and worries that Shiva, who is younger and prettier, will steal her thunder. She's nice to Shiva for the show, but she can't stand her. Yolanda made it clear that if Shiva's offered a spot on the show, she'll quit," a source told the 6 October edition of Star Magazine, as per Celeb Dirty Laundry.

This runs contrary to an earlier report stating that Foster and fellow cast mate Lisa Vanderpump were lobbying to get Safai as part of the cast in the upcoming season.

"Both Lisa and Yolanda are telling Shiva she needs to join the cast and they want her to appear on the next season," a source told Radar Online. "Shiva is not only gorgeous, but she is a true class act. Everyone loves her. In fact, despite being divorced from Mohammed, Yolanda encouraged him to marry Shiva. Yolanda and Mohammed have remained very close after their divorce because they have three children together.

"Lisa would love to have Shiva on the show because they are friends, and as viewers know, she isn't popular with other ladies and could use another ally!" the source noted.

Meanwhile, another new face to join "Real Housewives of Beverly Hills" is "The Young and the Restless" actress Eileen Davidson, who has already started fighting with Kim Richards, according to reports.

Filming of season five is underway, and Radar Online reported that Davidson has not made an attempt to get to know Richards, which has resulted in tension between the two.

"Eileen can come off as very snobbish and aloof," a source told the publication. "Whenever Kim and Eileen film together, there is always a lot of eye rolling on the part of the soap star. Eileen complains that Kim is a total airhead and doesn't understand why she is even on the show."