My computer has two hard drives that I use to store photos. My more recent files (of the last month or so) are stored on my computer's primary drive, and everything that is older is generally on the secondary drive. When I import new files, they are set to be saved in folders and subfolders based on year, month and day (2015\2015-01\2015-01-20).
Most of my photos are from my DSLR and are uploaded on a pretty regular basis, and there may be only a handful of separate folders created. When I import photos from my phone, however, the files are as old as 2 years. This causes a number of new folders to be created on my primary hard drive that just have a handful of photos each. Since most of these should be stored on the secondary drive due to their age alone, I would like to merge any new folders created due to the recent import with the folders I have already moved to the secondary drive . If I try to click and drag the folders, Lighroom tells me 'A folder named "XX" already exists at this location'.
I can click and drag the actual photos, but that will be much more time consuming due to the number of folders.
Is there a good way to merge folders within the catalog, from one location to another (i.e. move folder "2015-03-02" from hard drive A and merge with folder "2015-03-02" that already exists on hard drive B)?
this is not possible. You have to copy the files to the folders if they already exist. But you can choose the secondary drive as a target during import. An even better - you can save your import settings as a preset. Define two presets e.g. "new images to 1st drvie", "old images to 2nd drive" an choose the correct one during import.
If you have not already imported them to the "other" hard drive, importing them to the desired drive would be your best bet.
If the photos are already on two drives, you can merge them but not entirely within LR.
First you would need to use Explorer/Finder to merge the to groups of files into one directory tree on the one drive.
Then you would go into LR, Library module, Folders panel, and "relocate" the moved directories.
Test this with a small set of files to make sure it works the way you want it to.