The Winter Jazzfest, now in its tenth year, has grown into a signature event of New York’s jazz scene. Like the environment it reflects, relationships hold its keys to discovery and understanding. Saturday night at Judson Church in Greenwich Village, within a sprawling nine-venue marathon featuring scores of bands, composer Henry Threadgill had assembled a seven-piece group, Ensemble Double-Up, to premiere a piece, “Old Locks and Irregular Verbs,” in remembrance of his friend, composer and conductor Butch Morris, who died in January 2013. My account is here.