I read somewhere, probably in a translation of some Nomura interview, that the silver-haired guys couldn't feel Jenova like the Sephiroth Clones could in the game, so they gathered the children with geostigma (= jenova cells), made them drink water infused with Kadaj's will and made them point out the location of the head.

Why the kids pointed to the meteor monument, Nomura only knows. *drops asleep*