is it possible to pay for an item with paypal using someone else's paypal account? I have my own paypal account but not enough money on it and my sis has offered to have it taken out of hers, but im not sure if thats possible.
If your sister lives at a different address the seller may be unwilling to proceed with the transaction as he will lose all seller's protection by accepting the transaction.
Email your seller first and explain the situation.
Or ask your sister to move money from her PayPal to yours.