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:

