The Insert Field button in the template editor will allow you to easily insert fields from related objects. However, S-Docs can access related fields using standard “dot” notation that can reach fields up to 5 relationships removed if you manually edit the template source.
For example, you could include the following in your template:
If you find yourself needing to extend to a far removed field value, we recommend creating a formula field on the base object. In the example above, you could easily add a formula field on the Opportunity labeled PAowner_name__c and set its value to the field referenced above. Then, you could use this field in your S-Docs template.