Here's a
link to the CIP Q&A's that were updated this year. Your POA question is at the bottom of page 4.
From prior posts:
Speaking at the ABA MLES conference last year, Lisa arquette, Chief of the FDIC's Special Activities section, said that the CIP regulation does not include guarantors as "customers." She added, "Section 326 does not eliminate prudent underwriting for banks" and that normal underwriting mehods would require banks to adequately identify the guarantor. She emphasized that identifying the guarantor was a "separate issue entirely" from CIP compliance.
In summary, the law does not require you to CIP a guarantor, but common sense does. If the presence of a guarantor is necessary to make the loan a bankable deal and you want the loan to be valued at 100 cents on the dollar, the file should clearly indicate the guarantor's identity and credit worthiness.