I believe but can not prove that David Bly and Hannah (Anna) LaCoste?, Morgan, Bly are the parents of My Great grand mother Adeline Bly Heald (Hield)b 1818
I first found them in the 1820 (25?)census of Chautauqua co NY. Adeline was born there.
Adeline and John William Heald lived in Kendall co Woodford co. and Livinston co IL.
I have know idea where David was from or which family he belongs to. My daughters is working on this line along with me and discovered the possable LaCoste link
Any help would be appreciated Marlene