NICOLE RICHIE knows EXACTLY what she wants from fiance JOEL MADDEN for a wedding gift – another baby!

The former Simple Life star and her rocker beau are set to wed in a super-secret Dec. 5 star-studded ceremony at the Beverly Hills home of Nicole’s dad, R&B legend Lionel Richie, The ENQUIRER has learned exclusively.

And Nicole, 29, and Joel, 31, are already working on adding another bundle of joy to their family.

"The 100-person guest list is still being finalized, and invitations will go out any day," said a source close to the couple.

The maid of honor will be Nicole’s best friend, Masha Gordon, while the best man will be Joel’s twin brother, Benji. Nicole’s half sister Sofia and daughter Harlow will serve as flower girls, continued the source.

Proud dad Lionel Richie will walk Nicole, the daughter he adopted, down the aisle.

Guests are expected to include Paris and Nicky Hilton, Jessica Alba, Christina Aguilera, the Kardashian sisters – Kim, Khloe and Kourtney – plus Spider-Man Tobey Maguire and his wife Jennifer Meyer. Lindsay Lohan’s lesbian ex Samantha Ronson will DJ the reception.

Wedding buzz has been building since Joel confirmed their engagement in February. The couple, who began dating in December 2006, have two children – Harlow, 2, and year-old Sparrow.

It’s been a rocky road to the altar for the two. The ENQUIRER recently reported that Nicole had become consumed by fears that Joel was being tempted to cheat on her. She also accused him of making his career a priority over marrying her.

But Joel now seems to be committed to Nicole AND in late Septemeber Nicole whisked away pals including Christina and Sam  to a combination birthday /bachelorette party in Mexico.

Nicole’s fuller figure was the talk of the party and she’s had to alter her wedding dress to accommodate her added girth.

"IN fact, Nicole could be pregnant now.  She’s being very coy."