There is a marriage record for a Wylie J. Byrne at Familysearch.org. He resides in Coraopolis. He states his parents live there also.https://familysearch.org/pal:/MM9.1.1/KHXK-YGS
Also, there is a 1947 marriage record for a Harold L. Byrne, same city, same parents.https://familysearch.org/pal:/MM9.1.1/KHXN-VCF
Interesting since in 1920 both were living in the Alexander household and the mother's maiden name is shown as Alexander.
This appears to be the parents named on the marriage records in the 1910 census:https://familysearch.org/pal:/MM9.1.1/MGQQ-9VW
(It could be that the James W. on this census is Wylie J. in the marriage record.)
Perhaps that 1920 census isn't your Harry.