Industry contribution analysis question

I am trying to do a multi-industry contribution analysis and have built my model according to the tutorial posted on the website. However, beyond the contributions of employment, sales (output) and employee compensation. I want to include the impact of certain contracted services (e.g. trucking/hauling, maintenance/repairs, human resources/bookkeeping). Should these be included as a separate activity/event or do I need to do further modification to the model to add the spending to these industries? Brian Harger