PayPal API to send large number of payments to different people

We need to send hundreds of payment through our paypal account to our customers on daily basis. The task is being performed manually but it simply takes too much time! We need a fully working function in PHP that can automatically send payment to hundreds of users. In this function we must be able to set the following options: * Receiver email * Amount * Currency * Funding Source (need to be able to automatically select source in following order: paypal balance->instant bank transfer->credit card) * Sender address (need to be able to set "no shipping required") The function should return whether the payment was successful, if so return the transaction ID. We do not have MassPay feature so your php function must not use MassPay API.