Legal Question in Criminal Law in California

It is not a violation of probation for someone else in your home to engage in legal conduct. However, that does not mean you shouldn't be concerned.

I assume your probation terms make your residence searchable. The other members of your household have a reduced expectation of privacy because you live there and the cops can search any area of the home to which you have access.

Your family member should keep the medicinal marijuana in a locked container that you cannot open, and you shouldn't be present when it is used.

Don't count on getting away with a dirty test by saying you were in the same room whle your family member smoked marijuana. It is possible to test positive due to passive exposure, but it would take a whole lot of smoke in a very small room.

If there are drugs in the residence, yes, probably.