This is a rather old post, so I wonder if you haven't come across this information already. Son Frederick changed family name to Kemp or Kempf (I've seen it both ways, this line has since changed name to Kemp). I have more details on this family line, if you do in fact get this reply.
John Conrad arrived in Phil, Penn Aug 17, 1733 with his five children - (ship Samuel, Hugh Perry, Master). John Conrad was the son of Christian and grandson of Frederick Von Der Kempf of Canton of St. Kallen, Switzerland.
Nationality is Swiss, not German. All land grants, wills, deeds, & records show Kampf. The original King's Land grants 879 sq. miles.