into one catalog on one computer using one referenced set of image folders?
To combine or merge catalogs — or to move photos from one catalog to another — you import one catalog into the other.
Choose File > Open Catalog and select the catalog that you want to be the master, or primary, catalog (the one you want to add to).
Choose File > Import From Another Catalog and navigate to the catalog that contains the photos you want to add from. Then, click Open (Windows) or Choose (Mac OS).
In the Import From Catalog dialog box, do the following:
Under Catalog Contents, select the folders that contain the photos you want to import.
Specify how you want to handle new and existing photos. For more information on these options, see Import photos from a different Lightroom catalog.
Repeat steps 1 – 4 for additional catalogs or photos that you want to add to the open one.
For a video on combining catalogs, see Julieanne Kost's Merging individual catalogs into a master catalog on Adobe TV.