WHERE Statement Woes.

SELECT T1.*
FROM Cust_Table T1
INNER JOIN
(
SELECT Family_Name
FROM Cust_Table
WHERE Cust_Name IN ('Billy', 'John')
AND RowNum < 100
GROUP BY Family_Name
HAVING COUNT(*) > 1
)
T2 ON T1.Family_Name= T2.Family_Name
WHERE RowNum < 100



( This code above finds all the familys that contain either multiple billys and/or multiple Johns and displays all the duplicates ordered by the family_name. )

The problem is that what I want it to do is search through the whole table and find within each Family (Family_ID) who has both a sibling called Billy AND John (Cust_Name) wether they have multiple johns and multiple billys I don't mind as long as they have a minimum of 1 of each. I then want to just output all those examples only not anything else. An example of the table is bellow, I hope this helps. Thanks for your advice.


BEFORE
Family_Name CUST_Name
Bruce Billy
Bruce John
Bruce Mike
Bruce Oli
Smith Billy
Smith Billy
Harold John

AFTER
Family_Name CUST_Name
Bruce Billy
Bruce John