Dynamic Schema mapping with additional column (with existing column) in ADF

Question

We have a requirement where we need to use dynamic schema mapping in ADF. Here for instance if we have two tables with different schemas, we are able to load them to target (2 files) using dynamic schema which is stored in a table in json format. However, when we add an additional column to table_1 which is referring to an existing column in the same table it is not working as it is dynamic schema stuff.

Example: Source : Table_1 (5 columns), Table_2 (2 columns) Target : File_1 (7 columns : 5 from table_1 and two additional columns), File_2 (2 columns)

below is the pipeline design

Lookup --> For Each --> Copy Activity

Source Column : Student_Id Target columns mapped : Stundent_ID, Student_Identification_Number

It is achievable if it is an individual pipeline with additional columns or with SQL query. However, when we try to add additional column dynamically, it says cannot find column though it is available.

Is there any way to add an additional column to a table when we use dynamic schema. Any help would be really appreciated.

Thanks, JakeerS