Only issue I could for see
Trolls taking the big family names(Brutal, Enigma, Maphasy).
And other names would be taken to troll specific people, your Enguard family name for example.
I think that could be mitigated by having a small "claim" period, where those who have family guilds already could take the name. What I mean by that is, you'd have to gain approval by an administrator to claim the name. So those who already have family guilds wouldn't have to worry about being online the second the system is released to protect their name.
That period would only last a day or two, just to get the system settled in without massive hysteria.
Also, I don't know if they have the ability to make changes like that to the player card easily(they might, I just am not sure.)