The set up: rMBP with 16tb OWC Thunderbay 4 via Thunderbolt connection OS 10.11.3 Latest iTunes My iTunes library size is +400gb Situation: You would think that this is such a common issue that there would be something written about how to fix or accomplish this simple task. I'm newly married and my wife and I would like to have one iTunes library where all of the music is stored and yet allow us to have access to it with different profiles (Apple IDs). One Library of music but our own ability to create separate playlists per profile. We share the rMBP with different user log ins. We have Family Sharing turned on. That doesn't solve this issue. I just tried to get the Apple reps to explain and solve the issue I have with Home Sharing. We were not able to come up with a solution. At the moment they wanted both accounts to point to the same iTunes library located on the external drive. That lets them see the music but it still shows my playlists and preferences. If she changes anything it changes it on both sides. Can iTunes create separate profiles and source one music library? The obvious solution is to duplicate the library and tirelessly manage it under both profiles and I'm sure you can see the issue there. The second option is to conclude that the OWC Thunderbay isn't what I need and buy a NAS.