I think it's an utterly mad idea but one we may have to consider.

The problem is that we'd be creating a hostage for Moddey, the way Kingsley and the Players had to sit on that bloody Ridley for so long.

An Obliviation accident? The tragic misapplication of a routine spell? Believe it or not, I'd trust Snivellus to do it and be able to reverse it later, so Molly wouldn't lose her entirely.