I just thought of something else - start meditating in your room. But don’t just meditate - get printouts, books if you can, downloads of tutorials off YouTube, and talk about them every single time you get the smallest opening, become a total bore about the subject and if they walk in while you’re doing it, invite them (insist) that they join you or at least listen to you explain how meditation will solve their problems, and the wonderful things it does for health, etc.
If you can’t or won’t create a boundary through active methods, be sneaky and create one through being a single-minded maniac on this one subject so that the minute you break out your meditation clothes (comfy t-shirt and whatever) they run a mile.
If you’ve ever known a fanatical bore who pins you down trying to put their thoughts in your head, the kind of person you’re willing to do a 180-turn or be a bit late to something to avoid, you’ll understand the desired effect.
Also, if you aggressively over-share on the meditation, they’re unlikely to ask you what else you’re doing with your eyes closed sitting or lying straight on your bed.