majoria said: Actually not Raquel, but the woman from the past showed in the last episodes (Raquel seems to be some kind of clone of hers, it's never explained)
Doesn't have to be a clone. Anime's kind of infamous for having ridiculously far-flung descendants look exactly like the original, and have the same name to boot. So in all likelihood this woman's name is Raquel, too, even if it's not Raquell Casull.
She's not a descendant, at all. That woman died with no children. She was the sister of the "true" antagonist of the series. That Raquel and Shannon happen to look like this woman and her brother are more coincidence than anything, though it could also be called fate.
First of all, use the spoilers tag. Second, it's actually the masterplan set in motion by the originals that resulted in the Casulls having proper DNA reassembled by mixing and matching in their family line.