Insurance companies will differ on their guidelines but many will not insure cars from more than one household. The exception is for a college student in the same state as the parent's policy is held. If this is a big family with many cars at different addresses it is doubtful that most insurance companies would allow for the cars to be put on one policy since they reside at different ones.

Since insurance companies vary you will have to do auto insurance comparisons to see if there is a company out there that fits your needs for the multi-households.