Just re-read your post and I think you have one more problem in your query.

In words you have stated "to filter out any records where it finds those 3 Names that also have "Default" as the PName", but that is not what you have written in the code. What you have written in code means, that ALL rows that have anything else than DEFAULT in PName will be filtered out - not only those that match the NOT IN ('GLASSMAN','NANCY','LUDEMANN') condition.

So, if I understand correctly, you would probably need this:

AND (ISNULL([Name],'XXX') NOT IN ('GLASSMAN','NANCY','LUDEMANN') OR ISNULL([PName],'XXX') <> 'DEFAULT')