I have James and Rebecca's children as follows.....Benjamin, John, William, Unknown female, James, and George. I'm curious as to where you found Anne and Rebecca.
I'm not descended from James and Rebecca, but from a William Dotson, who I think was probably a cousin or nephew of James. There is a William Dodson on the 1840 census in Belmont Co. whose data fits, and later records show that William was born in MD. William married Catherine Lee about 1838.
I don't have proof of who James' parents were, but my belief is they were Benjamin and Mary Dotson. Benjamin is on the 1800 Calvert Co. census. He evidently died before 1810. There is a Mary Dotson living in Belmont Co. in 1840. She was living next door to Jesse Dalrylmple, who married an Anne Dotson, who I believe was sister to James. Possibly James had three other sisters who also went to Ohio. A Nancy Dotson married Daniel Breeden and on the 1850 census living with Daniel and Nancy was a Betsy Dotson. There's also a Rebecca Dotson on the 1850 census, born in MD, as are Anne, Nancy, and Betsy.