Insurance companies are excluded in their own right; this may be unnecessary.
If you are attempting to verify the existence of a subsidiary of a publicly traded company listed on a major exchange, your research would be the same as if you were trying to recognize them as an exempt person. You would go to the parent's form 10-K on the SEC web site and find your quarry on its list of subsidiaries.
If you want to avoid going through this exercise every time the sub opens an account, you will record its status at the CIF rather than the account level.
In this world you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant.