Intake is the 'Starter' Library. It may not have all the columns of the Main (target).
That said:
Easy-Peasy (assumes you are on the master)
On the Library Icon: Create Library: Create an Empty Library: Tick Copy Structure
That copies ALL custom columns and their settings as well
Then make any structure adjustments before using it, as needed.
Mine is actually on another PC.
I Pull (work is done from the destination PC over a network share) books to my main Library over a wired network. 4 Years doing this without issue. OTOH I first started trying to push to the main
, erratic.
As Always, Have a backup and use care when bending the Calibre approved guidelines
