Stacking Stats

Is it possible to make it so a hero keeps the stats it had before when it changes classes? I want it so you can change classes and level getting different stats.

Here's an example of what I want:
-Unit A has 3 strength, 2 agility, 1 intelect base stats. Upon level add 1 to each, so level 2 is 4 strength, 3 agility, 2 intelect.
-Unit A changes classes and becomes Unit B.
-Unit B keeps his level (I know how to do that) and keeps the stats he had before. When unit B levels it will gain 2 of each stat. Unit B gains a level to level 3.

The porblem:
Both units have same base stats. After Unit A changes to Unit B and gains a level it should have +1 all stats from leveling from Unit A's class and then +2 from leveling again, but as Unit B's class. What happens is Unit B at level 3 will have +4 all stats instead of +3

Define "changes classes".
Are you doing it using the Unit - Replace action? If so you may simply set the stats manually after you replace the unit...set the strength for example to 3 + hero level, agility 2 + hero level etc.

Im not quite understand what you mean, are you have problem with replacing/upgrading/changing class a unit from one another ? if that's so, try chaos.

By changing classes, yes, that's what I mean. And assuming setting the stats +hero level is a trigger i should be able to figure it out, thank you.