Unit Help

I want to make a unit that has its own attack. But when a certain unit is put in it, it gains a second, ranged attack that can attack while the unit is moving. How do I do that? I want it so that 2nd attack chooses its own targets, and whenever I add a new person into the unit (like an orc burrow or zeppelin), it gains another one of those independent ranged attacks. So if I put 6 people inside the main unit, it will have the regular attack, but also it can shoot 6 arrows at 6 different (or the same target, if it chooses) targets.

How the fuck would I do this? :D

Make a custom ability based off of the barrage ability. change number of targets to 1 and modify dmg range ect, accordingly.

The make a trigger:
Event - A unit (is Loaded into a Transport) [a generic unit event]
Condition - Unit Type of (Transporting Unit) EqualTo 'Your Troop Carriar'
Actions - Add 'Above custom ability' To (Transporting Unit)

note:
You will need to add an additional trigger for when the unit is unloaded, to remove the ability.
Also I haven't tested it so I'm not sure if having multiple barrage like abilities will stack.

I hope this helps ;)

I'm sorry for my retarded wording, so thank you very much for bearing with me ^_^