Hmmm that is a dilemma. How about saying something like since you started vaping you seem to have developed an allergy to cig smoke and would people mind not smoking or vape while playing and show them all your nice vaping choices.....and by all means go outside for a smoke? It's your house and as much as you don't want to be one of those ex-smoker types (nothing worse than that lol) at least you'll get some clean air
and it won't be like you're preaching. You can't help 'allergies' after all 