[OL]Ehlers/Ofchen? from Oldenburg

Dear List:
I have been researching my Ehlers family here in Texas and all information
points to Oldenburg. I recently received information that the wife of my
great great grandfather Frederick Ehlers (listed sometimes as J. F. Ehlers
and sometimes as F. J. Ehlers) was Elisa Ofchen. However, I cannot find that
surname on any searches, so I believe it is misspelled. Does anyone have any
ideas as to what Ofchen might be? They came to Texas in early 1880's. They
had children (born in Oldenburg): Gerhard (born Feb. 15, 1872), Anna ( born
June 16, 1876), and Fritz (born Feb. 17, 1879). Gerhard's death certificate
lists his mother's name as Margaret, with an unknown surname. Elisa and
Margaret may have been the same person, or Frederick may have remarried to
Elisa Ofchen before Fritz was born. Does anyone know anything about this
family or surnames?