Bloodborne creator Hidetaka Miyazaki likes to have his stories echo one another, both between games and even within a single game. If he can't get a specific story beat to work in one place, he'll try to reuse it in another. Pay attention to the general vibe of Lady Maria's story - a distant location gets exposed to a Great One, there's a church-led slaughter of all the residents - and you'll find that already existed in the main story before the DLC came out.
The game had a lot of changes during development, with things being moved around, pared down, or even deleted entirely in order to get it finished and out on time. One of those was the (now-optional) trip to the vampire-coded Cainhurst Castle, which is separated from the rest of the game world via cutscene travel and is, in its final released form, only about half as expansive as intended. Even its enemies are mostly a remix of ones from Dark Souls' New Londo. So it's not unthinkable that at one point the trip to Cainhurst was not an optional segment and instead a direct part of the main narrative path; but when that had to be cut, Miyazaki took the opportunity of "The Old Hunters" to take another shot at telling the full story he wanted to.
Anyway, the queen of Cainhurst Castle is Annalise, a tall woman with white hair, 
who wears a helmet that entirely conceals her face. Why do that unless her face was meant to be a reveal? Theoretically, when Cainhurst would have been a fuller part of the story, Annalise would have dramatically unmasked at some point, and we'd have been shocked to see the visage of our old friend, The Doll. Data miners have even found unused Annalise voice lines performed by the Doll's actor. But all that got cut, then later repurposed for the DLC and so now Lady Maria was her influence. There's a sliver of this original intent remaining, however: why else make Maria distantly related to Queen Annalise, if not to explain why they now have to look so similar?
