Paypal payment that depends on other users to pay a share of the entire amount?

Question

Perhaps this question would apply to all payment gateways, however, I would like to know about the best practice approach toward processing payments where an entire transaction is only valid when enough users contribute a given share.

1) Should payments be processed for each contributing user as they commit to pay and refunded when and if the amount is not reached (not enough users contributed)?

2) If payment is processed for each user at the time when enough contributing users are found and the goal amount is met, then there is the problem of the entire transaction failing if individual users default on payment.

What would be the soundest approach in practice?

Answer 1

You can try Preapproval function of PayPal. This will suit for option 1, which is safer.

API for Preapproval is here.