Events
Date of Birth: unknown.
Place of Birth: unknown.
Bartrum (Marchudd 5) gives Gronwy a number of 9 in his generational dating system, which implies a birth date of, very roughly, about 1300. His birth, presumably, was somewhat before 1300 as his father died in 1298.
Date of Death: unknown.
Place of Death: unknown.
Relationships
Father: Heilin ap Sir Tudur ab Ednyfed Fychan.
This relationship is shown by Bartrum (Marchudd 5). Roberts states that the Goronwy ap Heilyn of the period 1277-82 was probably not of the line of Ednyfed Fychan. I am not sure if that means Roberts is casting doubt on the relationship given here, or on the identification of this Gronwy ap Heilin with another.
Mother: Annes ferch Owain.
This relationship is shown by Bartrum (Marchudd 5).
Spouse: unknown.
Children:
Gruffudd married Dyddgu ferch Robert.
References
Bartrum, Peter C., “Marchudd 5” in An Electronic Version of Welsh Genealogies AD 300-1500. [The sources that Bartrum cites for Gronwy are: Peniarth 131 (74), written by Gutun Owain about 1480; Peniarth 131 (49), written early in the reign of Henry VIII; Peniarth 128 (282b), “Llyfr Edward ap Roger”, written before 1582; and Peniarth 133 (30) and Peniarth 176 (355) by Gruffudd Hiraethog (died 1564).]
Roberts, Glyn. “Ednyfyd Fychan” in Welsh Biography Online.