Question about Spell book

I've made an hero abilities wich is based on spell book.But i want that abilities in the spell book increase level by leveling the spell book abilities.But the abilities in the spellbook isn't heroe abilities and doesn't level.
Is there a tricky way to make spell book's abilities increase level as the spell book?

I know i can make 10 different abilities instead of 1 with 10 level but the problem is that the spell book abilities has 10 level and 5 abilities inside so i need 50 abilities it's too much

If there is no way of doing that without trigger i've already my idea to solve this problem with trigger but i don't want to increase triggers line if it's possible to do it w/o

As far as I know, you cannot do it without a trigger, sorry. But if you decide to use one:

native SetUnitAbilityLevel (unit whichUnit, integer abilcode, integer level) returns integer
Or
native IncUnitAbilityLevel (unit whichUnit, integer abilcode) returns integer

Naakaloh is right. You probably could do set level thing. Or, you can be stupid like me, who didn't think something like this could be fixed with triggers and do it by making 50 abilities XD