Options, since at present simply adding a new origin to the UI does not appear to be feasible:
Option one:
Provide a TEMPORARY character generation core override package that completely visually and textually overrides the Cousland origin and redirects the player to the start of the Chasind Origin. Scripting will need to be done to rewrite PC's flags from noble to chasind.
Pros:
We have control over what presets are available in chargen
Origin is fully integrated into SP chargen
Cons:
This is gross lmao
Will need to be manually inserted before chargen and manually removed at least before another playthrough is started if not earlier
Option two:
Provide Chasind origin mod as standalone module and somehow redirect it to SP campaign in Ostagar after origin is completed. More research is needed to see how feasible this is, if at all.
Pros:
Much less messy, much more compatible. Requires no work on the player's part
Cons:
Character generation options are at the whim of what the player has installed in packages\core\override
Any SP resources used (particularly in our version of the Korcari) will have to be replaced with/made core
Many more module resources will have to be provided as core to avoid breaking things on transfer