(1) Perhaps the design flaw is in the children.
The problem is I don't understand how the battery would shut down just lights and accessories without a) losing all your radio presets b) requiring entering the anti-theft code in the radio (risky because if you get it wrong you can brick your radio) c) still have power to know that you're trying to start the car.
It seems to me this requires more than internal battery smarts but changes to the car's wiring to have separate battery connections for computer, accessory, and starter.
Right now most cars have just one big post clamp for the + and - battery connections.