Good Ol' Tom

We are nearing our close of escrow on our new house and I am beside myself with excitement. We are buying the house from a very sweet family who grew up in the military and they are so kind to us. However, there is Good Ol' Tom. Tom is the oldest of the 5 children who are selling this home after their elderly mother passed away. He is currently living in our house-to-be with his sister, smoking and drinking up a storm. Apparently he is a raging alcoholic. Every time I have met Tom, he is sweet as sugar to me. My agent assures me that every time I am not around he is a handful, so I have been recruited to attend as many meetings with Tom as possible.
My first real experience with Good Ol' Tom (as dubbed by my agent) was during the house inspection. Tom d the inspector. Admittedly, it is very disconcerting having some stranger poke around your beloved home and point out every tiny flaw. But this was more than Tom could handle. It was 9am and Tom was fall down drunk. How is that even possible? He followed the inspector around, harrassing him and saying things like, "I'm not fixing nothing, I sold this damn place!" Then he would immediately turn to me and tell me that he'll fix anything I want. I can have any appliances I want - he'll even give me his furniture. To add to this odd behavior, every time I was left alone with him he would start talking about his mother, or the house or his childhood and then burst into tears and go running from the room, locking himself in his bedroom. A few minutes would go by and the whole process would start over again.
Let's just say item #1 on our to do list when we move in is to change the locks. I'm pretty sure Good Ol' Tom is harmless, but I don't want to get up one night and find Tom passed out drunk in my living room.