I believe General St Clair's daughter used the name Sinclair.From that, I can only go by Cemetery Records at Mckeesport.
I believe my family is connected to George Croghan who was Queen Alliquippa's Indian Agent.His daughter was married to Chief Joseph Brant.George Croghan was also the executor to the Gratz Brothers Estate. TheJewish Gratz Brothers were will connected to the Myers family of Ft Myers in Lee County Florida. Christopher Gist's granddaughter Marie Cecil Gist married Benjamin Gratz the son of one of the Gratz Brothers.My source on this is Americans of Jewish Descent by Malcolm Stern and the life of George Croghan with cemetery records mixed in. George Croghan was Catholic. His nephew William Croghan married into William Clarks family who were also Catholic.His grandson married into the O'Hara family of General James O'Hara of Pittsburgh.William Clark was Meriwether Lewis' partner.
This leads to the Phelps Gorham Purchase and to William Clark, William Cooper the father of James Fenimore Cooper and to Chief Logan of Pittsburgh/Wheeling and George Croghan. Then it goes to James Fenimore Coopers friend Ned Myers then to Major Michael Myers of Pittsburgh and Major General Michael Myers of Auburn NY and last to General James O'Hara of O'Hara Township Pittsburgh who was a friend of General Arthur St Clair of Greensburg.I believe Upper St Clair Township in Pittsburgh was named after General Arthur St Clair.
DAR records are a big help on whom is related to whom with these Generals of George Washington.This all comes full circle when George Washington and Christopher Gist visited Queen Alliquippa in Mckeesport New Years Eve 1753.I have a record that a 14 year old Surveyor Assistant Jacob Myers was also along.