true. this would avoid too much clutter.
but what we would need is merging tax codes based on prior transaction types. we cannot simply merge the newer inward tax code with the existing tax code which was functional for both inward and outward. that would be a disaster.
maybe Manager should first create separate keys for the existing tax codes based on the transaction types and then let the user manually merge them with the new tax codes. it could be 1 to 1 merge or 2 to 1 merge. for some reason i do not want any automatic script doing this. manual is better. we just need the function to do it.