She was there, but she wasn't twelve.
In her book A Paper Life, the Oscar-winning actress Tatum O'Neal alleges that Griffith dragged her, at age 12, into an opium-fuelled orgy in Paris, along with another actress and the boyfriend of one of the actresses. Tatum also alleged that she walked in on Melanie while she was in bed with her father Ryan O'Neal.
http://en.wikipedia.org/wiki/Melanie_Griffith