User blog comment:Ncduru/Who is Anna?/@comment-4999650-20151211101511/@comment-9595671-20151212054749

@Wrath & Ncduru: You know, its possible she could be both Lucy and Hisui's (and possibly Yukino and Sorano's) ancestors. After all, even a clan can have some of its members leave it, as long as some members stay to continue their traditions its fine.

So some of the clan members who left could have ended up becoming part of other families. I personally think the few Celestial Wizards who still exist after the Key of the Starry Sky arc are descendants of Anna's.

That could be the reason they're still Celestial Wizards, because their bloodline has something that kept them from losing that magic. Other Celestial Wizards learned it like common magic which is why they lost it.

@Umnei: They didn't get the original, they built their own Eclipse Gate to use. As we saw in Zeref's flashback, it was one of the things he had made in the past before he was cursed, so people could find the plans for it like the R-System.