I seldom use my front brake as the rear brake alone is more than adequate and if locked up the bike is far more stable than locking up the front wheel. I would have the front lever control the rear brake and forget about the front brake entirely. With newbies it was common practice to adjust the front brake so the rider could not lock up the wheel and be sent over the handlebars.
You can verify this for yourself by riding a bike and at 15 mph seeing how long it takes to get the bike to a complete stop using only the rear brake.