Due to the lack of information about the mother of Charles Russell Leonard, and my theory that there may be some confusion about the identity of "Sophronia Burrill", the reported mother of Charles Russell Leonard. Her name appears to be first hand knowledge given by someone, as no record to confirm this has been found.
A woman by the name of Sophronia Burrill was living in Elbridge, Onondaga, New York as early as 1850 until her death in 1883. Her name was Sophronia Campbell, wife of Nelson Burrill. The similarities between Sophronia, wife of Thomas Knapp, and Sophronia, wife of Nelson Burrill are astounding, leading me to believe the two could easily have been confused. Aside from their names, these two woman appear to have been born around the same year and they both died in 1883. Furthermore, the Burrills lived 11-12 miles east of Port Byron, where Sophronia Leonard reported her husband missing in 1833.
Was Sophronia Campbell married to Russel Leonard before she married Nelson Burrill? No record of either Sophronia's marriages can be found and no conclusive evidence has been found. The only evidence I found which may prove that Sophronia Campbell was NOT married to Russel Leonard is on the 1865 New York State Census, where "Number of times married" is asked and the answer for Sophronia was "1". (Note: Sophronia Knapp indicated she was married two times). People didn't always answer census questions honestly, however. A marriage record would still help positively prove or disprove my theory.
Following are copies of Nelson and Sophronia Burrill on the census beginning in 1840. From these we learn she was probably born in Onondaga County, New York, and her parents were born in Massachusetts.
Notice, in 1840, Charles Russell Leonard, would have been 10 years old. No children in the home match this age. He doesn't appear to have lived in Sophronia Knapp's home either that year, though.
Sophronia Burrill's death was announced in The Cayuga Chief, Weedsport, April 21, 1883, as follows:
An attempt to locate Sophronia Campbell's parents yield only one result so far. In Chester, Massachusetts, a daughter named "Sophrona", was born to Alvan and Polly Campbell on October 15, 1814. She appears to have had a brother named Nelson, born May 1, 1811.