It was a week for rockin' grandkids: Singer Chynna Phillips, 36 (left), announced the Dec. 6 birth of her third child – daughter Brooke Michelle, named after her grandma, "California Dreamin'" singer Michelle Phillips – with husband Billy Baldwin, 41. Then on Dec. 14, Liv Tyler, 27, introduced son Milo William (with rocker husband Royston Langdon, 32) to the world stage. "My baby is so handsome I can't stand it," Tyler told a friend. "He also has full lips." Just like his grandfather: Aerosmith's Steven Tyler.