I'm having trouble finding out how to change a general's portrait in RTW and BI. What folders are the general portraits and cards stored in? And what file contains the determining bit of code that assigns a particular portrait or card to a particular general? I'm not trying to mod existing portraits or import new ones; I'm just trying to switch out the existing generic portrait on one of my generals with another generic general portrait.

The reason I'm asking is because the two generals that my faction (Romano-British in BI) started with have the exact same portrait, with the only difference being that one of them is the "young" (heir) version and one is the "old" (leader) version (insert "I Am Your Father" joke here). This issue isn't affecting my game, but it is a bit aesthetically annoying.