Abilities through triggers

How can I make it so that abilities given to a hero through triggers (Unit - Add Ability) can be upgraded using the Hero Points given when you level up?

Hero - Learn ability

Completelly wrong.

The only way is to replace a learnable ablity the hero already has by using an Ability based on Engineering Upgrade, if you disable the ability based on engineering upgrade it will work.

I would preffer an alternative to using the Hero Abilities button though, you could make it so the hero uses another way to learn abilities then you just increase the level.

Once I saw in a map that every hero had hero abilities that were like Learn Ability 1 and that stuff so when the hero learned those hero abilities the real ability got increased in level