We have always taken the view that "did not receive" must mean "did not receive within the 28 day period to challenge or pay".
If you think about it, sometimes councils don't pursue matters for months or even 2 / 3 years, and there is the odd story in the press of a letter turning up years after it was posted. If a PCN arrived 2 years after the date of posting and the next day an order for recovery is served, it is obviously not the intent of the legislature that the recipient has no recourse and must pay the OfR, as that would be an obvious injustice.
I therefore recommend you don't add anything to any box, just get him to tick the "did not receive" box and leave it at that. As long as SD is filed in time, it's a tick-box exercise and the SD will be automatically accepted, and nobody could accuse "Ken" of making a dishonest declaration.
The key thing is to keep an eye on the amount due on the council website: as soon as it drops down to £65 you can make representations, you don't need to wait for the physical re-issued PCN to be served.
Top tip: If the order for recovery does not include a copy of the original PCN, that can provide a ground of appeal. It therefore recommend filming the opening of the envelope that contains the order for recovery, if there's no copy of the original PCN enclosed you might as well get some conclusive evidence of that.