Hi Barbie-Lew,
I did fiind the death certificate for Louis Conrad and noted the similarity of occupation. John Henry Frederick came to US in 1848, Henry (b 1807) in 1852, and Carl in 1857. Both Henry and Carl/Charles came from Bremen to New Orleans; haven't found JHF Miehe in a passenger list. The clues are tantalizing, but nothing definite that can connect any of them.
Paddy