[Sada]

qbds = query.addDataSource(tablenum(RDeferralsTable));
qbds.orderMode(orderMode::GroupBy);
qbds.addSortField(fieldNum(RDeferralsTable, DeferralsId));
qbds.addSortField(fieldnum(RDeferralsTable, Name));
qbds.addSortField(fieldNum(RDeferralsTable, AcquisitionDate));
qbds.addSelectionField(fieldNum(RDeferralsTable, Name));
qbds.addSelectionField(fieldNum(RDeferralsTable, DeferralsId));
qbds.addSelectionField(fieldNum(RDeferralsTable, AcquisitionDate));

qbds = qbds.addDataSource(tablenum(RDeferralsTrans)); !!!!!!!! косяк
qbdsTrans = qbds.addDataSource(tablenum(RDeferralsTrans)); объявите новую переменную для каждого ДС