Hi Dawn, I am also tracing MARSHALL ancestors in Northumberland County, PA. I don't want to confuse things by adding unnecessary info - and I know there are a lot of Marshalls! - but let me throw out some of my data anyway. Perhaps a name or place will ring a bell. There is no John that I know of at the time you mention but I am open to the idea that there could be...I do have a William, b. 1821, who later married a Magdalena (surname unknown). They had a son, John, born about 1844 and died 1866 (and another son, George b about 1854 who married Mary Shuman. There probably are other children I just have not located them yet.)
You see, this William is as far back as I have been able to go...perhaps he had a brother named John. William and his wife Magdalena are buried in St. John's Union Cemeter (due North of Watsontown). They lived in that area, I believe, most of their lives.
If you or anyone else can identify these family members I would very much appreciate it. Thanks, Sharon