Hi Sean,
I added information in the attachment. Hope this helps to sort out. Thanking you in anticipation.
Query for Scenario1:
SELECT *
FROM USER_PRFL up
INNER JOIN BSP_LOB_Grp_Lookup bl
ON bl.BSP_LOB_GRP = up.User_Group
INNER JOIN IMPACTED_LOB il
ON il.BSP_LOB_CD = bl.BSP_LOB_CD
WHERE BSP_LOB_GRP = 'CCSG Group'
This query fetches value of CCSG Group, but there are some more groups present in BSP_LOB_GRP column like (Site Group, Sales Group, LOB Group) and these group should belong to CCSG group. So you can find more in the attachment.