Originally Posted by Blackcat31:
Instead of rewarding the child, try rewarding the parent. Tell them the rate for a 3+ year old in diapers is 3x the regular rate and as soon as the child is trained they can be rewarded by getting the regular rate. 
I saw that suggested somewhere else but these are subsidy. Not allowed to charge anything but the .50c co-pay per day. But thanks Blackcat! It is a great idea!