Hello JBob.
I agree that a child will not appreciate the concept of Brake and accelerator being seperate actions and should not be undertaken together and I can imagine both pedals being in use together on some occasions.
Because of this I have included a power kill circuit on my build, this is operated by an application of hand or foot brake, It will also cut the power if the bonnet is not secured, and finaly, I have a plip operated relay box mounted under the bonnet, which cut's the power from upto a 100Mtrs away just in case my three year old grandson tries to escape. Sneaky eh??

There is the circuit diagram on the forum some where, can't remember where at the moment.

I see you have found the diagram.
Whoops, you beat me to the post JBob, I'm sorry the circuit complexity is a problem

Regards,
Brian.