LVS SPICE OVERRIDE GLOBALS and LVS SPICE PREFER PINS are rulefile statements that should help in this case. The first allows specification of pins during a subckt call even if those pins aren't actually listed in the .subckt definition. The second relates more to situations where pins are listed in a subckt definition, but also listed as global nets, and determines which should take precedence. So there is some overlap in functionality between the two statements. I don't think you'll need both, just whichever one seems to fit your situation best.