Lightroom: New external hard drive with the same name and missing files

Oh, Victoria, I hope you can help me! I've seen your replies to others but am not sure which applies to me. All was well in LR CC until I installed another external hard drive (and yes, I'm on a Mac). The problem may be that both drives are Seagate Backup Plus. I added 4TB on to the name of the original one, which has all the photos, so I could distinguish. This original 4TB has all the photo files, and LR previously saw it with all my files under the name without the 4TB appendage. The new drive (let's just called it Seagate) has nothing except my Time Machine backups. In the Folders panel in LR, the NEW drive (Seagate) looks like it has all the photos in it, albeit now with the ? next to all photosI I thought maybe because they're both Seagate Plus drives the Mac got confused. I tried changing the name of the 4TB to remove the 4TB part so it might see it again. Now that drive is greyed out in LR and it's still seeing what it was seeing before. I'm sorry if any of this is not clear, I know it's a mess. Help, please?

Note: This conversation was created from a reply on: Lightroom: External hard drives not displayed in my Library any longer..