What do we do when my stepson has rules here but at his moms he gets to control the home?

My stepson is 2 yrs old he beats on our dogs, at his moms his grandpa lets him do whatever he wants with their dogs cuz grandpa hits them. Also he will only take a couple bites of his food or none, at his moms she sets a plate of food in the fridge so he can get into when he pleases well i have other kids and when my daughter has meds she gets liquid that has to be refridgeirated. Also when we go by fastfood places he yells eat eat repetly and we cant afford to eat out alot but when we he does eat then. He throws things toys my daughters ds anything he can and time out nor taking things away dont help any, . He tries to be in control over everything anyone does in our home and will throw a fit every time he dont get his way i love him with all my heart but i want to put a stop to it all before hes any older. Any advice?