My understanding of PS4 Beta

[necrosis]

I was wondering if I buy a ps4 edition and register will I be able to log on to my account from both ps3 and ps4 simultaneously? I ask because my son has made a character on my account. Or would he have to start over and pay 2 subs?

You can not play on two charaters on the same account at the same time. Never have been able to do this even in FFXI.

So if you and your son use the same login and password to play FFXIV one of you has to make a new account and thus a new character.