Yes, Sarah, it appears this thread veered pretty strongly. But that happens quite a bit, and I've probably been guilty of "veering" it myself a time or two.
Anyway, yes, two witnesses to two separate incidents of the same kind has been part of the WTS official instructions for (at least) many years. No, it is not new. And, yes, children have very definitely been recognized as those "witnesses." (Although sometimes they're testimony has not been considered.)
Now if only they would turn these matters over to those trained to deal with them properly...