The 1920 census list Harold as Margaret's son and Robert as her grandson.Does not necessarily mean that Robert is Harold's son.
1900 PA, York
WEADON, Robert, 29, married 1 yr, b. VA, VA, VA
Maggie, 29, 3 children/3 living, b. PA, PA, PA
PARKER, Minnie, 13, b. PA, VA, PA
Harold, 7, b. PA, VA, PA
Bula, 6, b. PA, VA, PA
1910 PA, York, York
WHEADON, Margaret, 39, widowed
PARKER, Minnie, daughter, 23, widowed, 2 children/2 living
Harold, son, 18
Rula, daughter, 16
LAWSON, Robert, grandson, 5
LEE, James, boarder, 42, widowed, b. MD
Is it possible that Robert is the son of Minnie PARKER, who shows widowed and 2 children? and just goes by PARKER name in 1920 census?
You have the 1920 census
1930 PA, York, York
WEEDON,Mary E, 59, widowed
PARKER, Harold A, son, 38, divorced
Jerry C, grandson, 15
Elise L, granddaughter, 12
Hope this helps you some!Tried to find a Robert PARKER or LAWSON in 1930 York Co census with no luck.