Trigger marian or imperial reforms for AI

I am fairly certain this has been covered before, but I could not find anything specific with a quick forum search. I would like to trigger the marian or imperial reforms for the romans in my Pahlava campaign, so that there is a larger chance that I get to fight real roman legions. What do I need to change to set the unconditional reform dates earlier than they are now? How do the reforms affect AI players? Are the barrack automatically upgraded, or is the AI able to build the new barracks itself?

https://forums.totalwar.org/vb/forumdisplay.php?f=129