That's very interesting, thanks for the reply. I suppose this is one of those things that unfortunately may not exposed at the scripting API level

@Helmet Too Tight I am also not sure how campaign data is passed to battle data, but it is definitely not XML. XML is mainly used for UI structure and can utilize specific functions to affect the game slightly—for example, the "Dead Units Tell No Tales" mod actually tells the UI to disband units if they are mustering in the campaign.

No reinforcements for night battles are likely hardcoded. I assume it is possible to "spawn" the corresponding reinforcement units (perhaps not characters) during a battle, but I do not think it is possible to pass the corresponding unit casualties and experience to the reinforcing army after the battle.

Just out of my own curiosity (you're an expert at this :) ) - is it because the campaign manager doesn't pass reinforcements unit list to the battle manager when night battle is enabled? I poked around in the game files and the only reference to night battle is this line:
o.night_battle = pending_battle:night_battle()

I've never really understood how the game communicates the unit information between the campaign engine and the battle engine. Is it done through the xml files? I looked at the unit destroy mod ("Dead units tell no tales") and it seemed to only edit the xml, but I can't really make any sense of it. Would it be possible to add the reinforcements by taking local armies in the region near the night battle via script and feeding it through the xml somehow?

@Kylar I am afraid night battles' no reinforcement is hard-coded.

is it possible for night battles to get reinforcements too with a delay?

very good idea enhances realism

Thank you for continuing to mod this game.