Welcome Myangeleo, and thanks for starting a great thread. I hadn't thought much about communicating boundaries or not.
Here is a boundary I set and communicated with my family, I have been spearheading taking care of my elderly parents. They are in a facility but I take them to doc appointments, groceries, bank etc. My mom has alzheimers/dementia. Her doctor did a great job trying different meds and sent her to a neurologist. None of it made any apparent difference. The second time the doctor suggested Mom see a neurologist, I decided to stop the efforts to treat the Alzheimer's. I communicated my decision to my siblings and let them know if any of them wanted to spearhead more efforts, I would support them but I couldn't see any point in continuing myself. Doctor and siblings both agreed with my decision but I honestly would have supported a sibling who wanted treatment as I thought that maybe someone would have to do it as part of the grieving process as we lost our amazing mother.
I liked Lexiecats point that you can't really enforce him not lying. I suppose you could communicate a preference to him that he drink openly around you. Just a thought.