The selection of products in any shared catalog can be easily updated from the Action column of the Shared Catalogs grid. The changes you make are visible to members of any associated company accounts. The process is essentially the same as choosing products for a new catalog structure, except that the scope of the configuration cannot be changed.
Update the product selection
On the Admin sidebar, go to Catalog > Shared Catalogs.
For the shared catalog in the grid, go to the Action column and select Set Pricing and Structure.
Follow the instructions in Step 2: Choose Products.
You can skip the first item, because the scope of a shared catalog cannot be changed after it is saved for the first time.