I chased this one a long time, and still don't know, but here's what I found.
James (B~1695; D 3 May 1767) married Ann Wilson. James'will (Online at Chester County RootsWeb Archives) mentions wife Ann; sons William, Henry and Joseph; daughters Sarah, Susanna, Mary, Ann and Margaret; grandson James. son of John, deceased; Susanna Fleming, widow of son James and Ann McBeth (relationship not defined, my theory is that she was the widow of his son, John, and had remarried).
Probate; Ann "McBath"; Letters of Admin. granted to John Linn, 4/26/1808; Sureties Gideon Smith and And(rew) McLanahan; Northumberland co., PA.
In the book Annals of Buffalo Valley (1877 by John Blair Linn, Online at Union County PA RootsWeb Archives) the death of Annie McBeth of White Deer on 30 Jan 1808 is mentioned. It states that Annie was formerly of Cumberland County PA and notes that "She was twice married, first to John Fleming, and afterwards to Andrew McBeth...".In the same book, she might be the one listed as a pew holder in the Presbyterian church at Buffalo Crossroads. (see also page 271, where she might be the one referred to as "Widow Fleming", and John Linn is listed separately (he was her son-in-law).
Deaths Saturday, 30th January, Mrs. Annie McBeth, of White Deer, formerly of Cumberland county, buried at Buffalo Cross-Roads. Her ancestors fled from Scotland on account of religious persecution. They were of the first settlers at Brandywine, in Chester county. She was twice married, first to John Fleming, and afterwards to Andrew McBeth; had four children by her first, and five by her last husband.One of her sons fell at Long Island. - Argus (A newspaper)