[LE] Help with creation kit

[VanguardofSkyrim]

I am currently making a mod that is intended to change the armour of the city guards after the civil war. I'm not really a fan of how the armour that the guards are wear is permanently changed after the civil war. What I was thinking is that the I would change it to suit whoever you sided with once a hold was taken after the civil war is over. For example if the imperials take over the rift there would be imperial guards for the remained of the war but upon its completion there would be riften guards again. I thought of making this as I thought that once the war was finished the Stormcloaks would want to return the province to normal life, and the Imperials wouldn't want to appear as if they are being incredibly oppressive as this might insight more rebellions and also they had bigger problems coming with the Thalmor and may not have enough resources to spare city guards so wanted to somewhat hand back that responsibility to the locals governed by a new Jarl. The exceptions would be that there was still Stormcloaks in the Blue Palace (Solitude) to make sure Elisif (or other important members of Solitude) was not still loyal to the empire, and imperials in Windhelm due to the heavy Stormcloak population, many of whom would still be loyal to the cause, so they would be present to ensure that there was no attempts at another rebellion.

Anyway now that you understand what I want to do. How do I make the guards change from Stormcloaks/Imperials to hold guards after the war. I have played around and got the Stormcloaks to change in Solitude but this would not be different between taking over the hold and the end of the war it is the same from the moment the hold is taken for the rest of the game (irrelevant in Solitudes case but you get the idea). I know that it will have something to do with quest stages but I don't have a great understanding of it so I was wondering if someone could help explain it to me.

Thanks in advance