Sorry I did not reply to your earlier message because our computer has been down for some weeks.
We have considerable information about Arthur MORCOM and his descendants in Lead, South Dakota. I think we have you listed as one of his grandsons.
Arthur's grandfather William Henry MORCOM(B) was born c. 1822 in St Mewan, Cornwall and married Jane DUSTOW in Q4 1844 in St Austell.
I know very little about his grandson William's family. He died in August 1963.
My guess is that Randolph was Rodulphus J RUNDLE b. 5th April 1871 in Tywardreath (near St Austell) and died 2nd September 1949 in Georgia. His mother married first a John MORCOM, who had many relatives in Montana, but I cannot yet see any connection with your South Dakota MORCOMs.
I will be delighted to exchange fuller information but, as it will involve living relatives, you may prefer to contact me by email.