There was a large amount of cash involved - Euros. So a member bank of the ECB would make sense. There were two separate payments, supposedly, one for return of funds to the Iranians, the other for release of hostages. This bank may have been involved in only one of those (or neither, we are speculating here). If it was involved in the hostage money, it would be interesting to know how the funds were delivered and distributed. We had hints in the drops that some of it may have ended up in SA, for instance. "We have it all" covers this territory as well, I would think.
The best way is to hide it somewhere amongst 99 truths.