Baby needs to get into his own appropriately sized tub, pronto. a 15quart sounds good for a 120gram baby. If thats not working try a 6quart tub. A water bowl and two small, secure hides are all he really needs.
Do not handle that animal at all unless for routine maintenance until he is eating regularly. The family can wait to see him until after he's gotten established.
Your enclosure is probably very nice for your adult bp. But if the hides are big enough for the adult than they are much, MUCH to big for the baby. The refusal to eat, the strikes, its most likely all linked to stress.
Set him up in the 15quart, 2 hides the water bowl and proper heat and leave him for 7 days with no handling. Offer a live hopper mouse or small adult at night after pre-scenting and without removing anything from the tub if you can avoid it (maybe take the extra hide out so the mouse doesnt end up sleeping in it). Stay around but dont hover, just make sure the mouse doesn't bite the snake.