Possible to add a "shift right-click" action to a unit?

Like the title. Is it possible to order a unit to "shift right-click" something, or in some other way add an action the unit will perform once it's current task is done, with triggers?

You can chain actions with triggers yes:
For example, your unit must kill a unit THEN attack another unit

E - A unit dies
C - (Dying unit) equal to (unit)
A - Order (Killing unit) to attack (other unit)

But there is no way to add 'waypoint flags' through GUI (maybe JASS, but I doubt it)