Hello,
I was just wondering if you had ever just contacted the clerk in the county that Dexter lies.
They could tell you what years and if they have births for that time period and if there was a fire.

Dexter Village, Washtenaw county did have a Castello family living there, but I dont know what the relationship would be at this point. It looks like they were there as early as 1850.
Very possible Frank was there or maybe his family visted at that time he was born.

Did you find this yet?
Not to say its your family, but alot of the same names

1880
Cazenovia, Madison, New York

Martin COSTELLO Self M Male W 41 IRE R.R. Trackhand IRE IRE
Mary COSTELLO Wife M Female W 36 IRE Keeping House IRE IRE
Stephen COSTELLO Other S Male W 11 NY IRE IRE
John COSTELLO Other S Male W 9 NY IRE IRE
*Francis COSTELLO Other S Male W 4 NY IRE IRE
George H. COSTELLO Other S Male W 3 NY IRE IRE
Edward COSTELLO Other S Male W 4M NY IRE IRE

*this Francis Costello would have been born in 1876