Thanks for the information on PA currency. In 1763, John LEGG received 13 pounds 10 shillings PA currency on behalf of his CONN wife, whereas the other children of Thomas CONN each received 18 pounds MD money. There was a 25% differential between the values of the two currencies. One other heir, Samuel HARRIS, husband of Thomas CONN's daughter Martha "Molly" CONN, also received PA currency.
I wonder if John LEGG might have gone to PA (Washington County?) with his brother-in-law Samuel HARRIS, acquired some land, returned to Frederick/Montgomery Co. MD, and bequeathed that land to his son Thomas LEGG, and possibly to his other sons as well.
Thomas LEGG was in Montgomery Co. MD in 1783, where he signed an Oath of Allegiance that year, but is recorded as settling in Fallowfield (now Carroll) Twp, Washington Co. PA "before 1790". His younger brother Charles (said to have been b. 1763 or 1767 in Montgomery Co. MD [which was still Frederick Co. at that time]) arrived there in 1800, but stayed only five years before taking a flatboat to Cincinnati and thence to Butler Co. OH, where he settled. Nothing useful seems to be known about the other three sons of John LEGG and daughter CONN.
Audrey Franklin has posted that Thomas LEGG's first wife Anna NORTHCRAFT died in Washington Co. PA in March 1789, concurrent with the birth of twins Harriet and Althea/Aletha LEGG. If this is so, then Thomas LEGG must have moved to Washington Co. PA between 1783 and 1789. That seems like the right time frame for his father to have died and left him land in Washington Co. PA. Just a theory.