Yes, James Craig of Birdsfield was the son of John Craig and Mary ALEXANDER. It is correct that his brother, John Craig (1789-1876), married Margaret Wallace. Among the nine children born to them (John, James, Archibald, William, Basil, Jane, Mary, Alexander and Thomas) was my 2nd great aunt, Mary Craig (1840-1916), wife of William Paterson.
Cheers,
Rodeo