Setup Extensible Attributes for Service Tasks

Is it possible to setup Extensible Attributes at the task level in Teleservice?
I know that we can set them up at the Service Request level, but we would like to create a attributes at the task level.

As an example, for one task, we have to track 2 fedex numbers.

For a different task, on the same Service Request, we need to track 3 additional fedex numbers.

Any thoughts/ideas/suggestions are welcomed.