See California kills by Wildlife Services
From the post:
Wildlife Services is a little-known federal agency of the Department of Agriculture charged with managing wildlife, particularly the intersection between humans — ranchers and farmers — and animals.
This map shows where Wildlife Services made the most kills of three commonly-killed animals — beavers, coyotes and bears. The charts below show the type of method used to kill those animals.
You can select beavers, coyotes, or bears, with other display options.
There appears to be no merging on other names for beavers, coyotes or bears, as well as the means of their, ah, control.
A good illustration that sometimes a minimal amount of merging is sufficient for the task at hand.
Mapping locations of control activities onto a map with changeable views is sufficient.
Readers aren’t expecting links into scientific/foreign literature where mapping of identifiers would be an issue.
Good illustrations, including maps, have a purpose.
So should your topic map and its merging.