Web Portal Data Governance use bulk mapping adding mapping for derived field, getting Cannot create feature level link in the destination classifier that already contains a bulk mapping link" 

In most of the project related to Data warehouse it’s a very common scenario to flow the attributes as it is from source to destination with some addition derived fields. The entity name could be the same. 
In this case, if I use bulk mapping at entity then I cant add the mapping for derived fields, then below error is getting popped up "Cannot create feature level link in the destination classifier that already contains a bulk mapping link" 

Workaround for this scenario:

One may create bulk mappings and then re-designated the result as direct mappings at the table level. Do so like this:

1. Create a bulk mapping by creating a data mapping specification and dragging the schema(s) across to the target.

1. Right-click on a target table (where you wish to manually directly map one or more columns) and select "Expand"

1. Open the target table and note the mapping may now be edited and new ones added.