The lands of Calderwood and Dripps came into the Maxwell family in the 14th century but not through a marriage to anyone called Calderwood. As far as I know, no-one named Calderwood ever owned the lands. The first castle built there was a Maxwell tower in 14th century. East Kilbride is one of the Scottish new towns built after the Second World War (from 1947) so if your mothers folk migrated to the USA after 1950 they might have come from East Kilbride. Prior to the new town being developed I understand East Kilbride was tiny village of which a dozen of the old houses survive amongst the concrete and new bricks. Although East Kilbride is close to Calderwood the origin estate village was a small place called Maxwelltown to the north est of the castle.