"Record of PA Marriage prior to 1810" has: Marriages at First Presbyterian Church of Carlisle (present Cumberland county , PA and pretty far west of where you are looking.) oct 21, 1800 John McCune and Catherine Bell; other McCune, McEwen, McQueon marriages are to Culbertson, Stewart, Gregg, Anderson and Work. If these names are familiar there are dates and full names.
Genealogies of PA Families Vol 1 (A - E) has page 48 and 49:
Wm Bell farmer b. 1706 d. Oct 29, 1783 Paxson Twp. m. @1731 Paxon Twp Jane (Lea? or Thompson?) Children:
1.John Bell b. 1732 d. Aug 1810 Cecil Twp., Washington Co., PA m. @1762 Elizabeth Boyd Children:
Catherine m. John McCune
2.Wm Bell b 1743 d Dec 11 1813 Erie Pa m. 1799 Dorcas Forster children:
Sarah d Mar 6 1840 m Robert Heron
I don't know if this helps you at all. If the names are familiar, it could be that they moved west together or other family members did. This is all I have relating to Bell. Good luck, Bruce