User blog comment:KingFubuki92/The Issues with RWBY's writing, and how Volume 6 can possibly improve on them./@comment-71.30.17.231-20180123235423/@comment-3965075-20180124002336

Plus, didn't Qrow say that the souls of each Maiden merged with their successor? It could be that they can identify the "original/core/root" Maiden within their host through some method. I recall an episode of Avatar:TLA where Aang picked four different toys. He picked those because he held some of his predecessors' memories and recognized them to a degree. Perhaps a similar method is used for identifying the "roots" of the new Maidens.