It is highly unlikely that the Calderwood family ever had anything to do with Calderwood Castle. The Barony of Calderwood came into the Maxwell family at the end of the 14th century when surnames in the lowlands of Scotland were well established. People would have already adopted the surname by the time the Maxwells came into the lands of Calderwood. Calderwood is so called because it is a wood on the banks of the river Calder. The Maxwells built the first castle there. There was no family of Calderwood at Calderwood at any time as far as is known. The surname was probably adopted as a locality name as could of course refer to any woodland along the length of the river Calder and not just the barony of Calderwood. So clearly the Calderwoods are not related to the Maxwells or descended from them and according to my research have no relation to the barony of Calderwood either. Try 'Black's Surnames of Scotland' for the earliest referances to the surname.