The answer is no. In order to benefit from the student price of any travel package, you are obliged to have in your possession a valid (that has not expired) student card from a Greek University or Technological Institute (AEI or TEI), otherwise during boarding you will be fined by the ferry company, with the fine being payable directly to the ferry by you. 

IMPORTANT! If during the reservation process you register a participant as a student while they are not, or while they are not in possession of a valid student card from a Greek AEI or TEI and you get a fine from the ferry company during boarding, our office bears no responsibility