Based on the research I've done, the consensus here is that I need to complete 14 Additional Part 2 forms to identify the colleagues for whom the checks were cashed.
That's correct. You do need to list every payee as a person on whose behalf the transaction was conducted because that is obviously what happened.
Personally I really would not want to look any third party reviewer in the eye and say that I honestly thought the individual across the counter had cashed his friends' checks out of his pocket and was just replenishing his cash from us. (I don't like the look on people's faces when they clearly think I am stupid.) Legend has it that a call to the FinCEN Helpline might get you a different answer based on something called "The Fishing Boat Ruling." If so, document the phone call.
Of greater importance is making sure that it does not happen again via a policy that simply prohibits it; e.g. your bank will not cash more than 1 two party check for the same person and only then if that person is a customer whose account provides adequate recourse. Sending a single person to cash many "payroll" checks is emblematic of:
* human trafficking,
* employment of undocumented workers, and
* padded payrolls.
On anyone's scale of justice, your bank would be serving as an accomplice.