skrill is even more dangerous. they can just refund the buyer and also charge you for inappropriate usage of their service. avoid!
I believe Skrill is much harder when it comes to chargebacks so I would recommend it over PayPal and I don't think what you said is even possible. By that logic, If the transaction from A to B is made and then one user is sending to another, everyone will lose their funds? that would make the company close in a matter of days.