Legal entity borrower is an offshore Special Purpose Vehicle Limited Partnership that is a subsidiary of an offshore Pooled Investment Vehicle Limited Partnership, operated or advised by an SEC-registered entity. As such, are they excluded from the CDD Rule?

There are exemptions to both BO prongs for pooled investment vehicles. Unfortunately your situation doesn't match either perfectly. If you have in house counsel this would be a question for them. If not, perhaps a call to the FinCEN Help Line is in order?