Essentially the way I envision it working is that if you create a collection link within both collections, with some type of common identifier in the JSON attributes, and select collectionB.item2 from collectionA.item1, collectionB.item2 would show that it was linked from collectionA.item1.
This would build a two way relationship, which can be helpful. In my use case, I’m building a documentation site build of modules that have relationships to one another. I can do this currently, but it’s manual and not two-way. So if I make a change in the relationship, I have to make the change across multiple entries.