What I need:
Return record(s) that are not found in the Parent Tables

Combined Table has Fields ID,AssemblyId,PartsId

Parent Table One has ID,AssemblyId

Parent Table Two has ID,PartsId

What I tried that returns all records when I want only records that are not in parent tables.

Select *
FROM Combined
Where exists
(
SELECT a.*
FROM Combined a
WHERE somefield<>'2'
and NOT EXISTS
(
SELECT id
FROM ParentTwo b
WHERE a.id = b.Id
and a.PartsId = b.PartsId
and not exists
(
SELECT id
FROM ParentOne c
where a.Id = c.Id and a.AssemblyId = c.AssemblyId
)
)
)

Any pointers on where I'm screwing up would be welcomed.

TIA

Jeff