Why can't you just withdraw from your ATM (CASH ADVANCE) the needed money? If you don't have the money then a cash advance from a credit card.
Taking an cash advance from your credit card and giving it to the guardian in China then dealing with the extra hassle of paypal, wire transfer, unionpay etc.... Whatever extra fees or interest you may be in a credit card advance would be still cheaper then the various workarounds that will be discussed.