did the b1 guardians just knew about sburb?? i mean dad was the only one who seemed a little weirded out by everything. bro was splitting meteors and grandpa harley was going future into the medium...

Harley knew, he had the frog ruins that the game code comes from and owns the company the distributed it. Mom Lalonde worked for Skaianet so she knew. Dad probably had a vague idea based off the text Nannasprite wrote in 
Colonel Sassacre’s Daunting Text that got sent back with John as a baby.

Bro on the other hand, I’m not sure. maybe he’s just that cool, maybe Lil Cal told him about it  ¯\_(ツ)_/¯