In the Official Interpretations at 1002.7(d)(1)(2) where it states "It does not refer to someone whose signature is required by the creditor as a condition for granting the credit requested" mean that it applies only when we require the signature of a specific person-- as in requiring all officers or directors of a corporation to guarantee a loan for the corporation?

or does this also apply where we require a credit worthy co-signer in order to approve the loan of the applicant but of course do not require any particular individual?

If the person did not apply with the applicant and is on the credit because you required them as an underwriting condition then there is no joint intent to document.