I believe John Simpson Jr won the Kentucky Futurity with Panty Raid who was trained by his father in-law Stanley Dancer
John Simpson Jr. did win the World Trotting Derby with Panty Raid for Stanley Dancer, but not the Kentucky Futurity. She ended up trotter of the year. However, in the Kentucky Futurity, Simpson Jr. did win it for Stanley with Filet of Sole. John Simpson Jr.'s wife was Lois Dancer, which would make his father-in-law Harold.
