I searched through all the county books in the Hazleton library when I was working there (in Hazleton)on and off in the 1980's. I have a little bit to help you. In 1850m Sarah (widow) 63 had John 20 and Sarah 18 with her and liivng in the home of Samuel & Susan Muse.
I found no Fetter in 1840, but in 1830 there is Jacob Fetter 020001 - 0110001 which is two girls and 2 boys. Earlier in 1820, there are TWO Jacobs Jacob Fetter 100100- 20010 and Jacob Fetter 100100-00001
And there is a note: J Fetter of Sugarloaf, Luzerne County born in Berks Co, PA.
Jacob is such a common name that this is not a lot of help, but you may be able to work with it.