There is a small cemetery at the entrance to Boyce Park in Plum Boro, Allegheny County PA that contains the graves of the Aber family that settled in that area. The last grave is from around 1850, I believe. The cemetery is small but still well cared for. The tombstones have deteriorated from the weather but are still legible. I believe this will give you a starting point for finding some information on John Aber.