I gather that you too are a recovering alcoholic, just like your sister in law's dad. What goes for him should go also for you. It seems insensitive that she would assume that these "presents" are any more appropriate in your home than they are in the custody of your dad. She should send her "presents" elsewhere. I'm sure she has friends or relatives who could take care of this alcohol or drink it (although the "homemade hooch" may be unsafe to drink). They have no right to expect you to tough it out when they are unwilling to impose that responsibility on their dad. Put the "presents" in the garage and notify your sister in law. If the stuff freezes then it's their responsibility not yours.
W.