<question>Rally Point by trigger ?

I want to make a trigger when you select one or more buildings and set rally point. The unit produced will follow the rally point, but they ATTACK-MOVE to each of them instead of MOVE.

Can I set it by trigger?

I can set when a building set A rally point, and the unit produced by it will attack-move to it by several variables and triggers.

But how do I get it work when I set multiple rally points (with SHIFT)???