"His son Robert IV. of Knightley, who was summoned in 1301 to follow his king against the Scots with horse and arms, follows his father's steps and matches to good purpose with Alice Doyley, daughter of Sir John Doyley of Ranton and heir of her brother Henry Doyley of Cowley. She brought her husband the manor of Little Wyrley and overlived him two and twenty years, dying in the plague year of 1349. Their son Robert V. is a knight with broad lands in Staffordshire, Derbyshire, Shropshire and Berkshire, and dying about 1365 leaves a son and heir, Sir John Knightley, who is dead in 1393, the last male of the direct line of Knightleys of Knightley. A daughter and heir, Joan of Knightley, takes Knightley with her to her husband Roger Peshall, and their daughter, another Joan, takes the land from Peshall to Lee, marrying William Lee, a busy lawyer from Shropshire. They had no child, and the last lady of Knightley conveys away Knightley to her cousin Richard Peshall, to whom she had already passed away her shield of the arms of Knightley, excluding herself and all others of her name from any right in it."
↑ The Ancestor; a quarterly review of county and family history, heraldry and antiquities, pg 3 
It may be possible to confirm family relationships with Robert by comparing test results with other
carriers of his Y-chromosome or his mother's mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree: