I am descended from a different line of Vowinckel-Vowinkel-Fowinkle, but they all seem to have come from Nierstein, Germany. Right now part of the Vowinckel branch (now in Frankfurt) is in contact with part of the Vowinkel branch still in Nierstein. They asked about the history of Vowinckel, Pennsylvania. That caused me to start researching Vowinckels in Pennsylvania. I think you are probably descended from the Frankfurt group. Lord willing, I am going to Nierstein in July for a Vowinkel-Fowinkle reunion. I think the Vowinckels from Frankfurt will be attending. Perhaps we could share notes. If I am correct in my research, your great-great grandfather is descended from Anton Joseph Vowinckel 1820-1874 and Maria Katharina List 1825-1901, then from their son, George Frederick Vowinckel (1848-1915) and Kate Rodgers Walters 1855-1944, then their son Arthur William Vowinckel 1876-1947 and Grace Ruth Hulings 1882-1973 (I think they are the same as your "William and Grace Vowinckel" and the brothers and sister match. Sandy Fowinkle Mansel