Do you know the first name of the Parr father? Can you say whether the two siblings of Harvey Parr were also born in St. Louis?
There were three Elizabeth Parr's who died in Ohio, but not clear on where they were born. There was a William Frederick Parr born 4 Nov. 1885 who registered for WWII draft in 1942 at Newark, Licking, Ohio.
If the parents of Harvery Clarence Parr were found in a US Census with children, the search could be enhanced.