Ancestry of Richard Plantagenet & Cecily de Nevill
Lists his m to her niece of the same name & places s Robert to that m, however, dates make it unlikely, whereas dates work here
The cited information was sourced from Book published by Ernst-Friedrich Kraentzler in 1978 (Ref: chart 1150, 1061) The author/originator was Ernst-Friedrich Kraentzler.