SURPRISE WEDDING!

It was a, er, full house when Ashley Olsen and boyfriend of five years Louis Eisner tied the knot at a pal's palatial Bel-Air pad Dec. 28 in front of 50 guests.

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"Ashley looked gorgeous," an insider tells Star, adding that the fashion mogul wore vintage. "Her sisters Mary-Kate and Elizabeth were there. It was all very hush-hush." That's par for the course for the super-private pair. Longtime friends, the former child star, 36, and the 31-year-