If there is any way possible, get your family down to one vehicle. Make it a gas saver. Maintain it well and run it until it can’t be fixed.
If you live in a place where CNG is available, consider a conversion to CNG. (I actually don’t know whether this is good advice or not, since cutting off CNG or making it unaffordable would be easier for the government to do than cutting off gasoline.)
Regarding converting vehicles to CNG: Ranchers in west Texas have had dual-fuel vehicles for 50-60 years. Conversion kits can be installed by a mechanic in a day. Switch from one fuel to another, and back again, with the flip of a switch.