I'm not sure why you cannot find the records you seek, HOWEVER, I know that you MAY find something if you contact the historian at the Tabor Museum in Williamsport, PA. I, too, am researching this part of my family tree and am related to not only the Vanderbelts but also (if my research is correct) the Hepburn family as well through marriage.
I know that Peter had a connection with Judge Hepburn so I'm wondering if perhaps out of friendship and/or loyalty to the Hepburn family he became a guardian to Charles.
As for newspaper articles, I would try a search on The Lycoming Gazette. If memory serves, it is one of the first if not the oldest newspapers for that area.
If you wish to contact me directly so we can exchange notes, my e-mail is email@example.com