Re: american foul brood
Since we are playing the "Hypothetical Game" let's think about what might be the result of not saying anything to the people who got those hypothetical nucs which came from the same parent colony as the one you have which is now showing AFB.
Should one of those folks have their hive(s) come down w/ full blown AFB and they recall where it came from, the seller will be exposed over and over again on beesource and throughout the sellers community. Not good for business. Not good for one's reputation.
Do the right thing and retreive and replace the nucs. Or retrieve and reimburse. There is more to lose here besides some bees and equipment.
The answers are the end. The questions are the journey. Journey on.