Managing them with Marker Lists is best practice.
An alternative is to:
- Select a topic to add a legend to
- Open Map Index: Click +, Insert Legend into Map
- Select the Legend parent topic
- Open Map Parts: Select folder, Add Selected Topic(s)
Now you have a map part which can be added to any map. The tags are then available on that map.
Neither process copies the Resources. I suggest creating a topic with includes all resources and saving this as a Map Part to reuse on other maps.