Any system handling funds should be approached from the angle of minimizing the potential for fraud. If you don't do that right from day one there will be a lot of hard lessons which are more than likely to kill your company. Please team up with a company that has the experience to deal with this, balanced (which should have been your first gatekeeper here) dropped the ball in a terrible way, their anti-fraud measures should have definitely tripped over this so clearly they're not in control of the situation. From your posting and the comments here it is clear that you have the right general idea but you lack the relevant experience and tools.