What I gleaned from that post is that WW was not the grandmother that reported having seen them in December, and that she has never had foster kids. And that she believes her son.
From that I personally surmise that JWs mom was the one that says she saw them in dec, that she was the one that took in the 4 others for vacation and that she is the one with foster kids that she brought over to the house after the boys went missing.
From that I would also surmise that investigating JWs family at casa loma apartments, specifically her mother might bring to light any inconsistencies or possible knowledge of what happened.
Pure speculation and personal opinion of course!