You must have observed this feature on various blogs and forums sites. The Title of main topic of discussion is on the top and there is the plus sign clicking which we get the tree view of all the previous communications regarding that particular topic.
CRM also has the Communications feature built in. We can maintain the link in Communications by creating follow-up tasks. Why not have tree view structures as explained above in CRM so that we can have a track of an entire communication thread for that particular topic? We have a component which does the same. This component is designed to work with the Person entity and working of the component is pretty much straight forward as shown in the below screenshots.