Warning: This is not my normal area. I am not a lawyer.
(1) Do you have record of the dog biting your son? Medical records?
Lots of parents take their children to the liquor store. Maybe not stellar parenting, but you're not going to show it DAMAGES the child, so still not impactful for custody, yet.
But...she also said: then proceeding to drink the contents of the "little bottles" he buys in front of my son before driving home. If it is a 50 ml bottle, that is the equivalent of 2 shots.
So dad is drinking and driving with son in car....I would have a lawyer check into if he has been busted on any alcohol related charges lately. I'd also be asking the lawyer if a hair sample drug/alc test could be obtained.