Don't forget the mileage accelerator bonuses which could add up to a lot. A random search gave about 15000 bonus miles flying J.
If you decide to take the upgrade route, then your family would earn 19000 miles each on a flex fare, and mileage accelerator miles in addition. At 105000 for a SFO-DXB, 45000 for a DXB-CCU and 135000 for a SFO-CCU upgrade, these could potentially be used to upgrade a DXB-CCU sector every time they fly if you're short of miles to upgrade all the sectors.