Karl Marxhausen has a website that includes some photographs that seem to date back to the early 1960s. This photo shows Reinhold, Paul and Karl (on the right) "outside the igloo we built up on the upper bank of Concordia's football field."
The picture below shows Karl beginning his artistic career, following after his father. You can see at Karl's website that he is an excellent painter whose works people buy.
Below is a picture of Karl as a boy playing in a puddle. I think I had rubber boots just like that. They were part of the uniform for Seward boys in those years.
Karl's website includes images of all the pages from a small, illustrated book that Reinhold Marxhausen made to record a walk he did with Karl and Paul on a day in February 1963. Here is the book's title page:
Below is a sample from inside the book. This page is on the left side:
This page is on the right side:
The entire book is on this webpage.