I was glad to see your query on the Jens family. My grandfather's name was Eggert Edward Jens and somewhere down the line it was changed to Edward Eggert. My grandmother was Nora Hagedorn.
Have been in contact with a Jens in Germany to see if we are related but they were all given so many names that it's hard to locate them. I do have family photo's of Marx and Anna if you would be interested.
I did not have the information on Marx's parents though that will be helpful. I'm still trying to locate information on Helene. If I can help you let me know. Thanks Tammi