Basically, now that we can change the de jure lieges of duchies and kingdoms, it is in theory possible for us to create a titular title that would be identical to, say, e_iron_throne, with the exception that its coat of arms would be the Baratheon stag. Then, we could use a series of events that would replace e_iron_throne with e_iron_throne_baratheon whenever a Baratheon took the throne, switching over all claims and de jure vassals so that effectively, nothing changed but the CoA and the ruler history. Thus, we could start with the Iron Throne's CoA being a Targaryen dragon, and then have Robert change it to a Baratheon stag after usurping the throne.
There are three major problems with this:
- It's computationally expensive. As the number of titles that can have their CoAs changed and the number of houses whose CoAs they can be changed to goes up, the amount of events the game needs to check increases.
- It requires us to make a bunch of new titles that are mechanically identical to mechanically important ones. In other words, even if we only added e_iron_throne_baratheon, every direct reference to e_iron_throne would have to be changed so that it would also work with e_iron_throne_baratheon instead.
- So far, I've only been able to change the de jure lieges of titles that currently have a holder. If somebody can figure out a way around this one, that will eliminate the last hard obstacle to implementing this idea.