Dianne, it has been 10 years since your message was put here, but I recently noted the marriage in Posen of the couple you mention. It is found in Margonin (Kolmar Co.) Posen records, #5 in 1860-- the marriage of August Prechel, age 23 y, 2 m. (so b ca 1837) and Florentine Laura Weckwerth, age 24 y., 9 m. (so b ca 1835). This is indexed in the Poznan Marriage Project (Lukasz Bielicki). Likely this couple, residing not far from the other Prechels or Proechels mentioned here, was also related to them. Check Margonin parish records for details (LDS Family History Centre nearest you).
I hope this is still of use to Dianne or to other family members. This couple emigrated to Brown County rather than Waseca County, MN. Ken Neumann