I think what you want would be better accomplished with a custom field. Tracking codes were originally conceived to monitor performance of divisions within a company, where revenues and expenses can be allocated via appropriate tracking codes. Trying to do brand analysis with tracking codes requires you to allocate all income and expense to one brand or another. The income might be feasible, but how will you allocate rent, electricity, legal expenses, etc. to a specific retail brand? Unless you segregate your business activities by clothing brand, tracking codes are not very suitable, in my opinion, for what you want to do.
If you use a custom field, which can already be set up to show as a column, you can export and perform all sorts of analyses in a spreadsheet after filtering by brand. I think you would have much more flexibility. Sometimes, accounting tools just are not very useful for product sales analyses, because you are not really analyzing accounting transactions, but rather analyzing secondary characteristics of inventory movement. Your goal is to provide a method for separating the right transactions for examination.