Insuring multiple vehicles and/or drivers on an auto insurance policy may prove cheaper than having each of those drivers and vehicles insured separately on multiple policies. That's because insurers typically offer bulk rates to policy holders willing to insure several vehicles and/or drivers on a single policy. But such discounts typically adhere to guidelines that dictate eligibility. For example, if the head of a family wants to insure his or her children on the same auto insurance policy he or she has, then those children typically must list their parents' home as their legal residence. Blood relations also may influence eligibility for multiple driver policy discounts. In general, only blood relatives or relatives by marriage can benefit from multiple driver discounts. However, non-related motorists who jointly own a vehicle may be eligible for discounts.