How to relate two hierarchies to each other
A map design question for experienced mappers out there.
I have two separate hierarchies (trees A and B), each of which is designed to minimise duplication - each topic belongs in its place without much ambiguity and each level encapsulates its subtopics.
I need to relate topics in tree A to topics in tree B with many-to-many relationships. A topic in tree A may relate to several in tree B, and vice versa. Ideally, the connection itself would also have a comment or status. Every topic in each tree will connect to one or more topics in the other. We could approximate the number of connections as the sum of the topics in both trees.
What approach(es) would maximise the clarity and usability of the inter-tree connections? If I navigate around tree A, I would like to easily see the status of related topics in tree B and vice versa.