I don't have any more information on William McNAB, born 1822.
Of the other siblings, I know that:
Betty McNAB (1824-1899) married Henry Carey CLAYTON.The couple immigrated to NZ in 1869.
David McNAB (1827-1891) married Jessie BENNET.They immigrated to Sydney, Australia.Before that David bought oak for shuttles Scott-McNab in Norva, Russia.The couple had 10 children: Ann (1858), William (1860-1926), Susan (1862), Charles (1863), David (1864), Alexander (1865), John (1869), Elizabeth (1870), Jessie (1873) and Hector (1879).
Charles Gray McNAB (1831-1906) married Janet HAGGERT in 1855 in Dundee.They had 10 children: Alexander (1868), Charles (1870), David (1873), William, George, Jessie (died young), Elizabeth, Mary, Jessie, Ann. Charles married Helen WATSON in 1868 in Dundee.The couple immigrated to NZ.