Fred,
The surname OHNMACHT is so uncommon (there are more in the USA than in Germany) that a German researcher believes that, amongst 80 million Germans and only 275 OHNMACHT, that they must have originated from a common ancestor.
The fact that my gg-grandfather arrived alone in 1854, could lead me to believe that other family members came before him. If you'd like to share what you've found, I would be interested in trying to make a connection. Thanks...Ron