You're mixing regulations and state law. Before determining your regulatory responsibilities, you must have a contract. In this case there are two contracts--a credit agreement and a pledge of collateral. Contracts are governed by your state's laws and are enforceable in the courts of your state. How, when, and to what extent contracts can be created, modified, extended, or otherwise altered are legal considerations which must be discussed with bank counsel. After you and counsel have agreed on the best way to meet your customer's needs with contract documents that will stand up in court, THEN you look at the regs to determine what must be disclosed, how, and when.
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...gone fishing.