I did find a Stephen Wilcox and Charles an Jane Wilcox on Find A Grave for Hillsdale County Michigan. This Stephen Wilcox died in 1900. The Stephen that you said is on the 1950 census with Charles and Jane, was 73 years old in 1850. The Stephen I found was born in 1819. Do you know what the relationship was for the older Stephen an Charles an Jane Wilcox? Could the Stephen that I found be your Stephens son?