With the merging function, you can add to one catalog's disks (with the categories and descriptions) to another catalog
To do this:
Open the first catalog file (this catalog will be added to another catalog to create the merged catalog)
Click on : File->Merge ... choose the second catalog file (this catalog will have another catalog added to it)
The current catalog is now the the two combined. (The first catalog is unmodified.)
To save the merger, save the current catalog
Categories and descriptions are also merged. Distinct categories and descriptions are added as part of the merge.