please please please clear something up for me that i've wondered over and over again. ive read hs 3 times and this confuses me to no end: john created him and the other 3 kids, AND their guardians (well, nanna wasn't really one, but w/e). they all got sent to earth in john's session. how is it that the other 4 kids were created and sent to earth from john's session to theirs if we literally saw the babies get sent back and become guardians? if those were the only 8 kids/guardians made, then...?

When the Scratch was initiated the portals that sent the babies to Earth changed.  So the babies were sent to different times.  The babies that grew up to be the beta kids in the beta timeline grew into the guardians of the alpha kids timeline and vice-versa.