Paris Hilton isn’t the only celebutante with a new BFF.

P.H.’s child chum Nicole Richie has become close to fellow rock n’ roll wifey Ashlee Simpson over the past few months, Hollywood spywitnesses blab in this week’s edition of In Touch.

The A-list mamas have been snapped shopping together in Los Angeles, and in their 2008 holiday card, Ashlee and her Fall Out Boy hub Pete Wentz urged fans to donate generously to Nicole and boyfriend Joel Madden’s children’s charity, The Richie-Madden Foundation.

Now Ashlee is turning to her pal for tips on caring for newborn son Bronx, who made his arrival on November 20. After all, Nicole is already mother to daughter Harlow Winter, who will celebrate his first birthday later this month.

“She’s been there for Ashlee since Day One,” says the In Touch source.

In the wee hours of a L.A. morning last month, Nicole was the first person Ashlee called in when she had trouble getting Bronx to fall asleep.

“Nicole basically told her to call any time day or night, if she needs some moral support or help.”

The spy adds, “Ashlee has an amazing connection with Nicole, and that’s why she’s relying on her.”