All 3 Uses

successor
in
The Phantom of the Opera
(Auto-generated)

The retiring managers had already handed over to their successors the two tiny master-keys which opened all the doors—thousands of doors—of the Opera house.†
Chpt 3 *

successors = replacements
They bequeathed the whole mystery to their successors and heaved a sigh of relief when they were rid of a business that had puzzled them without amusing them in the least.†
Chpt Epil.
I then spoke of the two successors and expressed my surprise that, in his Memoirs of a Manager, M. Moncharmin should describe the Opera ghost's behavior at such length in the first part of the book and hardly mention it at all in the second.†
Chpt Epil.

Definitions:

(1) (successor)
replacement -- typically a person who takes the job of another person, but it can also be a thing that replaces something else
(2) (meaning too rare to warrant focus)