I stumbled on a Youtube video on this feature and thought it would solve a problem I've had for a very long time. It uses one resource to drive another, but not vice versa, so I can finally have a Bible drive a commentary, but be able to move in the commentary without loosing my place in my Bible. I was enthused.
However there's a gotcha. I linked my Bible to a commentary collection, in this case my collection of commentaries on Mark thinking I would see my bible and next to it a commentary pane that would allow me to shift through the commentaries in the collection.
But what happened was that Logos opened a number of the commentaries in the collection (apparently not all of them) as shown below. That's not as useful and certainly doesn't address the long-standing problem I described except in the limited case of only using one commentary at at time.
