Sorry for the joke, I just couldn't resist! ...of course your friend wouldn't make anything like that up, even if he was just trying to impress you. So what if they all do smoke together? It sounds fairly healthy and something to look forward to be doing too when you will be having a new family of your own. Just keep it like that. The worst thing that could happen is that your folks might "borrow" your stash during a "drought" or vice-versa...respect their wish or you might spoil the good balance you guys seem to have.

..oh one more thing: watch that spelling! "their" and not "there" and you mean "his mum" and not "her mom" surely!

...keep cool, one day your dad will take care of it if he thinks it's worth bringing it up. Trust him.