Alright, here's the guild Melina was in.
Also, I've noticed that there hasn't been a dark guild in the canon that tried to be a family, like Fairy Tail.

[b]Guild Name:[/b] Iron Enigma
[b]Guild Mark:[/b] [url=http://fc01.deviantart.net/fs70/f/2012/140/3/0/fairy_tail_oc_guild_mark_luna_fang_guild_by_brom290-d50fab7.jpg]Image[/url]
[b]Guild Leader:[/b] After unfortunate recent events, Melina's Father, Gregory Vale, now runs the guild. He is adept in enough kinds of magic he always seems to have another trick up his sleeve.
[b]Guild Orientation:[/b] Chaotic Evil, willing to do about any unsavory activity to forward their goals and make money, preferably from the shadows.
[b]Guild Motto:[/b] "Guard your family's name well, and strike with the shadows."
[b]Member Count:[/b] 29 (30 on Official Roster)
[b]Top Members:[/b] Delilah Vale, Mark Zerrit, Grant Vale, Serma Cathris.

[b]Fun Fact:[/b] Mayt's Edolas Counterpart was in the Edolas counterpart of this guild before joining Phoenix Wing's Edolas counterpart.

If I need more specificity, tell me.