You may have seen some of my past queries here for the Dallas family of Bedford Co, Virginia.Yours should belong to them, but not sure just how.I would be interested to know what you do have on your Robert Dallas, as for dates, places, spouse, and children ... if you can.
Also ... you mention a second Robert Dallas.What info. do you have on him also please ?
My Robert Dallas married to Nancy Turner, and I would guess he was an uncle or cousin to your Robert Dallas that married Phoebe Morgan.
Hope to hear more from you, and feel free to contact me at this e-mail also:jonericthomas @ aol.com