ALLENTOWN, PADiehard Eagles fan Bill Ferris said Monday that he loves his 12-year-old son Rex more than football, excepting the thrilling playoff games, of course. 'When I tell you I love my son more than football, you better believe I'm saying something important,' said Ferris, a 38-year-old accountant. 'I wouldn't think of missing Rex playing a shepherd in the church nativity scene this Sunday. That's because the Eagles clinched the NFC East, and probably home-field advantage, too.' Ferris said he has yet to form a plan for next month, when a playoff game overlaps with his son's band concert. 