The Idea is, since everyone has to buy an account service anyway (in form of game+DLCs)
It would be handy, if you could mark (with proof of relation, or by limiting IP adress range..) family members which then would lower each additional accounts monthly fee.

Just an example:
one account 13EUR each month
2 accounts 13+7EUR
3 account 13+7+3EUR

As it is now, not only does every family member (kids, wife) have to buy the full game+dlc, but also each one has to pay 13EUR, which is not a low amount if you would have 3 family members to join you (39EUR ... ).

So just a suggestion, I am aware that probably SE is not going to see this