I want to track all costs that go into a single campaign (ie. one company did the graphic design, another company did the writing, etc.). The default "Actual Costs" field isn't sufficient. As such, I was thinking of creating custom currency fields to break down each cost. But how can I add the values of those custom fields together as one "Total Cost"?
Use case:
1. Create a campaign.
2. Add value to "Actual Cost" field.
3. Track all additional costs for campaign. For example, cost of hiring a 3rd party to write the content for a print add.
4. Create new custom currency field called "Additional Costs" to track the additional costs and enter a value.
5. Create a custom "Total Cost" field that adds the values from the "Actual Cost" field and the "Additional Costs" field.
How do I complete step 5?