Susannah Maule was the widow of John Maule, son of Thomas Maule (in turn the son of Thomas Maule of Salem, Mass.) and his wife Zillah Walker. John and Susannah had six children (who have numerous descendants). John died in 1793 of yellow fever contracted while attending Friends Meeting. After John died, she and the children lived for a while in Radnor Twp (almost where I now live) and then removed to Frankford in Phila County, where, according to the notes shown to me by descendants of John and Susannah, she "married a man named Harper." This must be the Robert Harper you mention. Did they have children?
John Maule, son of John and Susannah, married Hannah Harper, daughter of Evan and Elizabeth Harper. Hannah was born in Canadagua, NY.
Sarah Phillips, dtr of Hannah Maule (in turn dtr of Benjamin Maule, another son of Thomas Maule and Zillah Walker) and Isaac Phillips, married Samuel Harper of London Britain Twp., Chester Co, Pa, son of John and Mary Harper.
I do not know if there is any relationship between these three Harpers.