I was wondering about this as well and no-one seems to have a definitive answer. I started my game in the Blue Square North with FC Halifax, which was formed in 2007 after Halifax Town went into admin. There are no rivalries or derbies, which I thought a bit odd as the fans are still the same so you'd think the team would inherit the old rivalries (Huddersfield and Bradford probably being two examples). I was hoping that some of these would develop over time....