Multiple mobile devices in folder structure, how to merge?

What @JohanElzenga shared explains what you see in your catalog. Each mobile device is treated like a virtual disk. The images are actually in the Pictures folder on your computer. You can manually move them the way he suggested, but LrC do it for your automatically. You need to choose a new location for the mobile image downloads in the preferences > Lightroom sync tab. Find the option in the middle of the panel to choose a location for the synced images. I recommend choosing an external hard drive. You can also choose to have the images organized by dated folders when they download. After you change this location preference, LrC will ask you if you want to move the current images that are in the Pictures folder. Be patient. This could take awhile with a lot of images, but eventually all of your mobile downloaded images will be collected in the same location.

These are not folders, they are devices. Like (virtual) disks. You need to click on the triangle in front of the name to see the folders. Then you can drag and drop the images into any other folder, just like you can do with the other images on your hard disk. After you have done that, you can remove the empty folder(s) of such a virtual disk from the catalog. When all folders of such a disk have been removed, the disk itself will disappear automatically.

In Preferences - Lightroom Sync you can define a normal folder as the destination for images that are downloaded from your devices, so new devices will no longer create new virtual disks.

Couple questions to start -

1 - If you expand the folders under the iDevices, are the images shown ones that you actually took with the cameras on those devices?  In other words, were you using Lr Mobile on those devices to take pictures and sync those up to the cloud?

2 - In LrClassic, open your Preferences, go to the Lightroom Sync tab and look for the Location section.  Is "Specify location for Lightroom's Synced images" checked or unchecked?

If the answer to #1 is yes & #2 is unchecked, I think that's what's going on.

When you take a pic in LrMobile, the full res image gets synced from the device up to the cloud.  LrC's sync will then pull down that full res image.  If you don't specify a location for LrC to store those images, it tucks them away and manages them in its own spot/way.  Sorry, but I don't know where that is on a Mac.

When LrC is doing that management for you, I believe it represents the "location" of those images in the Folder panel as the devices they were originally taken on.  Your dragging & dropping problem is because "Cory iPhone" isn't really a physical folder that the images are stored in.  It's just a virtual representation of what LrC is managing for you.

I don't manage my stuff this way, so this is all a bit of an educated guess.  For me, the much cleaner/more logical way to handle this is by setting that storage location preference to a "Mobile Downloads" folder in my normal folder structure.  That way, when LrC pulls down any of the images that I take with my mobile devices, they show up there.  Then I see them and can work with them just like any other file/folder.

Hope that makes some sense...

So, I'm trying to figure out how to merge these and keep them consolidated before I have a confusing array of folders.

My opinion, and I realize not everyone wants to do it this way, is that you should ignore the Folders and organize and search by Keywords. Then you can find the photos you want by keywords (which is a natural thing to do), without having to remember which of your mobile devices took the photo (which is a hard thing to do correctly).

Again, dragging from one to the other does not work...not sure why?

Explain what you are doing, and explain what happens.