agree that best is move out.. even if the smokers go downstairs to smoke, their clothes will have the smoke particles which are considered 3rd hand smoke... equally bad as 2nd hand smoke... just like my neighbours who smoke at service yard and the smell come into my house where I'm drying clothes... these particles will attach to the clothes (including babies') and that's harmful to babies.
my hubby is quite a smoker as well... and even my dad. but they tends to go downstairs and smoke instead. however, we still decided to go get a air purifier to put at home. especially in spaces where more smoke smells lingers. it do helps quite alot to clean and filter the air for my newborn as well.
you can get air purifiers to put in each room your baby stays in. it helps a bit but it will not remove all the harmful smoke particles. best is if you can move out
Hate such selfish low life so much. Hope you figure out what to do soon.
Talk to your hubby to talk to your brother in law, perhaps this helps
?