Moncrief is a Scottish name, and familysearch.org entries suggest they were Presbyterian, so they probably came from further north in Ulster down to Monaghan. Spotten mostly an Ulster name, and given the abundance of William Spottens in the Griffith's index, I suspect of English origins. If you know their religion in Pennsylvania, that may guide you to some Irish church records--Anglican, Methodist, or Presbyterian. Church records are your best bet for the time period you want to search. If it's any comfort, you're lucky to have traced them back as far as you have. Diane