I think to ensure better visits I’d keep visits short. 4 days. Maybe 5. Maximum. No time for it to go sour

The only people I can tolerate for a long time and can stay with long time in their house is my daughter and my grandson. There’s no one else I want to have in the house for more than a few days or stay in their house long.

When we go to my husbands sister or one of my stepkids out of state, it’s a long weekend type of visit or 4-5 days. They do the same. Last time we arrived on Wednesday and went home on Sunday. It was perfect length

Unless you are extremely close and have the best time together, keel visits as short as possible

Now I might be totally wrong but relatives not having return ticket would really bother me. I need to know when they arrive and when they leave. I am a planner. Is your sister spontaneous type? If not, she might be bothered by ambiguity.

Unfortunately I do not have a good advice re alcohol. I have hard time around drinkers and I saw some bad situations at events when people drink. If you can’t avoid drunken company, the only thing I’d suggest is to not drink yourself, don’t discuss anything controversial and go to be early/blame headache etc