Is it permissible to transfer an amount in euros to my bank card, then give its equivalent in dinars to the sender's family?

It is permissible to hand over the amount to your friend's family if you exchanged it from another person. However, if you are to pay the dinar from your own money and keep the euro for yourself, this is permissible with your friend's permission, according to the Hanbalis' view that an agent may take from himself for himself, even in currency exchange.