Last summer, Bob Dylan and Willie Nelson handpicked multi-national Americana band the Greencards to open their entire summer tour of minor league baseball stadiums. A few months, later the quartet seems to have caught the ear of another member of the extended Dylan family. While jamming with Rosanne Cash in Albany, NY Friday, the Greencards met guitarist/fiddler Larry Campbell, who served in Dylan’s band for almost a decade before linking up with Phil Lesh last fall. After talking shop, the Greencards invited Campbell to join them onstage last night at New York’s Joe’s Pub. About halfway through the group’s set, Campbell joined in, adding auxiliary fiddle to a series of bluegrass covers including a tribute to the Carter Family. Tomorrow, the Greencards will perform at Cambridge, MA’s Passim Folk Music & Cultural Center.