Scenario editor question: is it possible to add a new action to a unit?

Scenario editor question: is it possible to add a new action to a unit?
Because there doesn’t really seem to be a trigger in the scenario editor to add a new action/ability to a unit?
Like giving a unit a special action besides the basic action.
Or to add a second action.
For example allowing a unit to attack and to shoot arrows as a secondary attack.
And maybe to ‘set anim’ for a unit.