Are you suggesting that the belief in other people's experience of the same phenomena is also a false memory or that there was collusion to reinforce the false memories once they were recounted?
I think Lam's suggestion that they are false memories based on integration of a variety of real and imagined occurrences slanted towards a specific interpretation, which is something a group can do as much as an individual, is a lot more credible.
People looking for repressed memories of child abuse seem to be at least as good at generating false memories as at uncovering them.
TTFN,
WK