What is the score used in making the credit decision? That would be the score to report.
2. Credit score—multiple credit scores. When a financial institution obtains or creates two or more credit scores for a single applicant or borrower but relies on only one score in making the credit decision (for example, by relying on the lowest, highest, most recent, or average of all of the scores), the financial institution complies with § 1003.4(a)(15) by reporting that credit score and information about the scoring model used.
Borrower 1 middle score 732 Borrower 2 middle score 688
688 is the lower of the 2 middle scores and if I'm reading your post correctly 688 would be score relied on for making the credit descision.
The opinions expressed are mine and they are not to be taken as legal advice.