is it possible to lock units during a campaign?

[Chrysantheme]

I am wondering if it is possible to lock units during a campaign. In other words - is it possible to create a mod to use RotS-units in the sengoku jidai campaign, but a version were the RotS-units are only recruitable until certain arts are mastered? (for example: at the beginning of the campaign, it is possible to recruit the katana/bow samurai from the RotS-DLC, but once the art "Way of the Sword" is mastered, these RotS-Samurai can't get recruited - instead of them it is now possible to recruit "katana samurai" or something else.

I just need the information if something like that could be modable.

[Chrysantheme]

No one knows if this is possible? Or is my english that bad? ^^

I am thinking about a mod wich gives the player the oportunity to use gempei-units in the early campaign, but in the later campaign the gempei units should get locked and the sengoku jidai units should replenish them.

If i would buy the RotS-DLC, then only for modding purposes - so i need this information before i spent my money. ^^