Carolyn, it sounds to me as if this is a coincidence. Juliet Pierpont (daughter of Rev. John Pierpont and Mary Sheldon Lord Pierpont) married Junius Morgan in the 1830s. John Pierpont Morgan (J.P.) was their son, born in 1837. I don't know of any relative of Junius who married any Pierpont related to Juliet, though it's possible.
The Pierponts are not blood relatives of mine. Mary Sheldon Lord Pierpont's brother, Henry Edwin Lord (known as Edwin) of Litchfield, CT. was my 3-great-grandfather. His parents were Lynde Lord, Jr. and Mary Lyman Lord. The Lords' next-door neighbor in Litchfield was Lyman Beecher, father of Harriet Beecher Stowe and Henry Ward Beecher; he is a distant relative of mine through the Lyman family, who also are progenitors of Franklin D. Roosevelt. FDR's grandmother was Catherine Lyman Delano, thus FDR was a third cousin of my maternal grandmother.