What happened, if you are using such combination ?
SELECT
TS.MasterID,
TS.RecordNr,
TR.MasterName
TR.Date1,
C.MasterName
FROM TABLE_SUB TS
INNER JOIN TABLE_C C ON TS.MasterID = C.MasterID
INNER JOIN TABLE_R TR ON TS.MasterID = TR.MasterID AND TS.RecordNr = TR.RecordNr