So what should the EXPIRY_DATE be for the records coming from Part 2? Current Date or perhaps NULL? If it should be NULL, you can set it like this...
SELECT MEMBER, EXPIRY_DATE
FROM
(
(Select A.MEMBER, C.EXPIRY_DATE
From ABC.MEMBER A - - - - - - -- - - - Part 1
Inner Join CDE.DATE
on A.TAX=C.TAX
etc.......)
UNION
(SELECT B.MEMBER, NULL
FROM BCD.MEMBER B - - - - - - - - - - - - - Part 2
etc.....)
)
GROUP BY
MEMBER, EXPIRY_DATE
Does that help?
Noel