Is it possible to have the Tare Weight on a Traded Unit calculate the Tare Weight based on the associated Packaging Material Specs AND there sub-components? (Sub-component Packaging Material Specs associated on the Related Specs tab)
There is currently no out of the box way to go down to the sub components on a packaging spec when calculating tare weight.
As a workaround, a save validation event could probably be created to calculate and populate the tare weight field on save. You can learn more about validation events in the extensibility guide inside the extensibility pack.
Please submit an enhancement request around how you would like to see tare weight calculated.