User blog comment:Miskos3/Fairy Tail Episode 234: Tartarus arc Prologue: The Nine Demon Gates, Review/@comment-4933386-20150523124945/@comment-7418318-20150524074326

I doubt that's the case.

Deliora is a Demon from 400 years ago and later in the manga they mentioned that Doriate was like Minerva, a Human converted into a Demon.

Besides Deliora is a completely artificial Demon from what we know, so it doesn't have any relatives... unless you count Demons created by Zeref as it's relatives.