About changes and/or combining Hero Specializations.

The main question of the topic is: how much and to what extent can a Hero's Specialization be changed (beyond the "RPG file")?
The main points at the moment are:
1) Is it possible to change/replace existing specializations themselves?
2) Is it possible to supplement existing specializations, at least with effects from already existing other specializations?
3) Is it possible to create new Specializations from scratch? Or do they need a "template" like creatures, Abilities, and other things, which cannot be easily created?
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* There is no question about whether it is possible to change a hero's Specialization. We can already give, for example, Rutger the Specialization of Railag. The point is about changing the specializations themselves and their effects, which they will give to the hero.

Added 7 minutes later
For a simple example, let's take the following:
Let's say we want to create a new Specialization for Nibros based on existing ones, specifically by removing his bonus to Luck and adding Krag's Specialization. That is, as a result, we want to get the following effect.
"The enemy cannot use Tactics. At the beginning of the battle, your hero performs a special attack, and the strength of his attacks increases by 5% for each level."

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Or another example, where we might want to create a Specialization for the Order based on the Tent. Based on Kaspar's Specialization. But since the Plague Tent is not available to humans, we want to give another bonus in compensation. For example, part of the "Perfect Knight" Specialization or a permanent Divine Strength from Isabel's passive ability.