John,
Katherine never remarried. Family history says she emigrated 1848 from Pfalz, Bavaria. If you have records indicating they sailed together in 1850, please share as this is news to me.
We believe Charles/Carl was in 2nd Infantry Regiment of Baden Army. The Baden Revolution collapsed in July of 1849. We have kn idea how Charles/Carl escaped imprisonment in Baden.
Katherine collected widow's pension until her death in 1914. As far as U.S. Army was concerned, he was in service to his country when he died in 1862.
There are four generations of my family buried at Old St. Marcus Cemetery. My Grandfather's oldest brother, Charles (Doc) Steck had a daughter who lived only four months. Buried in plot owned by her grandfather, George Martin Steck, the gravestone of Ethel Steck is now embedded in the circular memorial wall near Gravois.
Just don't know where Charles/Carl is buried . . .