Thank you for the response. Tracking my family has been interesting. Unfortunately my ability to track Johannes and Karoline has been limited to post arrival in Philadelphia in 1873 and 1871 respectively. Prior records may still reside in Germany. Some church records may also exist in Philadelphia. Four generations of the family resided in the same neighborhood.
And a hint for your research. I note you also have an interest in Northampton County. There is a family of "Dux" currently located in Warren County, NJ immediately across the Delaware River. I've never linked them to my family.
Good luck in your continued search.