It's a rare event that we get a Mary-Kate and Ashley Olsen public outing, let alone a reunion with their younger sister and Marvel star Elizabeth ... secretly welcomed a baby boy last year ...

Mary-Kate and Elizabeth Olsen Have a Rare and Very Stylish Sister Date in N.Y.C. Go Inside Mary-Kate and Ashley Olsen's PFW Show for The Row — Ashley's First Since Welcoming Her Baby John Stamos ...