John and Denise,
If I may add more to the puzzle, I find a John W Evans marrying one Rebecca Miller in Cass County Illinois on 12/16/1847 Cass Marriage License # 35. Given the age of the children and the location of the marriage it sounds like we have the happy couple. Cass county is just up the river from Meradoscia. Never could speel. :) I think we have Rebecca's maiden name here to boraden the search.
Frank