Trying to trace Isaac DADDS - father and son.

Isaac DADDS married Ann Philpotts in 1864 in Bristol Register Office, although both were born in Swimbridge, Devon. On the marriage certificate his father is listed as Isaac DADDS, Ag Lab, deceased. From the 1881 census I calculate that Isaac jnr was born in 1841.

International Genealogical Index lists Isaac DADDS marrying a Mary in Swimbridge, Devon in 1840 but I've not been able to trace that record, nor a record of Isaac's birth. So I've listed what DADDS were registered in Barnstaple to see if any of these are children of the elusive Isaac & Mary DADDS