In 1810, Samuel Penrose built an additional farmhouse on the property for the use of his son, William and his new bride, Anne Lukens Larrett. In 1820, Samuel bought a farm in neighboring Warminster and by 1821, he had sold Graeme Park to his son, William. William managed Graeme Park with "Steady habits, honored and respected by all who knew him." (Bean's History of Montgomery County). Together with his wife, Hannah, they made Graeme Park "a rich and productive land, one of the most valuable farms in Eastern Pennsylvania." (Biographical Sketches of Leading Citizens of Bucks County, PA 1899)

William died in 1863 and Abel Penrose, his third son, bought the property from his siblings after the estate was settled in 1865. Abel had married Sarah Beisel in December of 1856 and had four children at Graeme Park. There are references to Abel's interest in preserving the Keith Mansion through his ownership of the estate, even giving tours on occasion.

Abel died in 1893. His obituary honored him as "highly respected in the community, a man of sterling character, a good neighbor, and a kind friend."(Public Spirit 1893.) His son, Morris Penrose, took over the property.

Like his father, Morris conducted tours for school groups and historical societies through the Keith mansion, while continuing the business of farming. During the summer of 1914, over 400 people walked to Graeme Park from the trolley stop at Easton Road.

In 1920 Morris Penrose sold Graeme Park to Mr. Welsh Strawbridge of Chestnut Hill, PA.