Create a user editable column to assign gl codes to specific transactions

In excel we usually created a data validation table inside an empty column so that the user can decide where to code their expenses to a gl account. As a manual edit. to a column of transactions so that the user can code them theirselves.  Then the updated categories were uploaded so that we can see what areas we were over or under budget. With PBI, I am uploading the same reports but by default they don’t come with this extra column inserted with a drop down option from a validation table. 

I want to avoid having to manipulate 30 sheets before being allowed to upload into PBI for transformation and modeling. 

Is this possible?