I certainly know about the family - being the author of the tree www.jearnshaw.me.uk
My gt gt grandfather was William Blackmore born in Burrington in 1826. Thomas Blackmore was not a Baptist Preacher but a Plymouth Brethren Preacher in Burrington.
Although not born in Devon I have recently moved here - to Burrington where the Blackmore family lived in the early and mid 1800s
I have a photo of Thomas Blackmore's grave in Burrington but I don't think there were gravestones of any others of the family as even the transcription of MIs done in 1917 only mentions one - Mary Anne wife of William (a station master at Fremington)
Please contact me directly at email@example.com as I'd love to find out more about the parts of the family who emigrated to USA. I've lots on the UK and Australian descendants