I can't help with a connection to Dorcas but I can shed some light on Riley Kerby. The Riley Kerby you found is most assuredly William Riley Kerby. My gg-grandfather was Avery Kerby, one of his sons. Unfortunately, Riley has been as far back as I have been able to trace and I don't have much info at that. Sorry that I can't be much more help. I do not have the time to do research anymore so I've had to put it aside for a while. If you would like more information on Riley's children I can share what I have.