"I do not think it can be corrected, Harry," Albus said then, heavily. "Not in any meaningful way, that is. And by that I mean not in such a way as to take those who already know out of danger. Judging by the conversation I overheard, however, they are aware that their children and their friends' children are attending lessons with them. Whether or not that bodes well for our efforts, they are in fact aware.
"Those who do not suspect anything have likely been taken in by my previous excuses and gave the matter no further thought, so I do not think we need concern ourselves with them. Those who do know or suspect must now be taken into our confidence. At the very least, knowing that their surmises were correct will stop them comparing notes with and bouncing ideas off their friends and acquaintances in the meantime.
"Therefore, I would suggest also making them aware of the danger they are in, if nothing else; teaching them to protect themselves, as well; and hoping against hope that they do not see fit to spread the rumours any further, and in turn endanger others," he concluded, allowing himself a small, mischievous smile aimed at no one in particular.