I have evidence which suggests that Harvey and Tillie Abbott had no children.
In an "Affidavit of Heirship" executed Feb. 4, 1976 "in the matter of the estate of Marie Henrietta Dilg Thompson, deceased", the affiant, Peter Carl Dilg, a first cousin of the deceased, basically provides an "inventory" of all the relatives on both sides of his deceased cousin's family, in order to establish heirship rights.
His deceased cousin Marie Henrietta Dilg Thompson, was the daughter of Henry Dilg and Lovina Abbott.Lovina was a sister of Harvey Abbott.The affiant Peter Carl Dilg testified that he was "well acquainted with the family history" of both the Dilg and Abbott sides of his family.
In the Affidavit, he states:"That Harvey Abbott (#2 hereinabove in Maternal Paragraph A) married an individual whose name is unknown to this affiant; that they never had any children born to them and never did adopt a child; . . . "
Granted, he didn't know the name of Harvey's wife, but he seems to have known that they had no children.Harvey was 43 years old when he married Tillie.
I am a great-grandson of Theodore William Abbott, who was a brother of Harvey Abbott - two of the six children of William and Wrispa (Lowe) Abbott.
I don't know if this helps you, but it's fun to find others with names in common, so I couldn't resist replying.