OP, what's your end game, I'm unclear? If you say what this is, then I'm certain that better advice would follow in its wake.
And let's be clear what the legal (contract law and PoFA) position is, to do which you have to read the sign. There is no other starting place.
The sign states that 'Failure to comply ....will lead to a parking charge of £100(reduced to £60 if paid within 14 days) being issued to the vehicle's driver'
...which is absolutely clear but still misunderstood by creditors. Just read what it says, not what it might have said, but what it says.
Has a penalty charge 'been issued to the driver'? No.
Why?
They couldn't be bothered to put boots on the ground and staff the site (and issue a penalty charge to the driver but instead have relied upon ANPR and sent a PCN to the keeper telling them that the driver is liable for a parking charge of £100.
This is not issuing a penalty charge to the driver, neither does the sign state that liability arises as soon as the breach occurs irrespective of whether they demand a penalty charge.
So, what must happen if you name the driver? IMO, they receive a demand for £100 discounted to £60 if paid within 14 days because these are the terms of their contract which has NOTHING to do with you, it's as if you, the NTK and everything else have been air brushed out of history, it's the two principals to the contract.
AND the sign, therefore the contract, makes no reference to dispute resolution so as regards their contract they don't have to offer this. However, their CoP requires them to do so and therefore they would.
So, is your aim to get the charge reduced to £60 and that's it or what?