Fashion designer Elie Tahari's plan to stitch together two penthouse units on the Upper East Side has hit a snag. Again. The designer - who has sparred previously with the board of 860 Fifth Avenue - is now suing the co-op's governing board for $50 million, claiming it has stymied his plans to combine the apartments. The suit - which names 14 current and past members of the board - alleges a "bitter dispute" between [...]