Forcing Yuezhi to invade anyway + adding units

[Connacht]

I wanted to ask two things:

- the first one is that I know that the Yuezhi are active only if you control Chighu with specific factions (and the most western ones still exists), but with the Seleucids I don't want to do a long travel in the NE corner of the map, through steppes and Saka armies, only for seeing the Yuezhi active. So I thought to modify the EBBS in order to force the Yuezhi to start an invasion even if you don't control Chighu.
Unfortunately I'm not expert in scripting and I fear that if I try to modify something I would do nothing or, worse, see undesiderable effects in game or even CTDs.
So I'm here, asking for some advices. What should I modify precisely? Thanks. ;)

- the second one is related to units. I wanted to add some minor units available to other factions, but they need an image for unit stacks (otherwise it will be a black vanilla Roman peasant as you know). I don't know precisely how to implement them, maybe I can try to modify some files but also here I think that I may do something wrong altering files (and I also don't want to load, quit and reload many times EB if I see that modifies don't work and I need to exit and continue to modify).
I also think that I should modify the building file, adding those units to the rooster of recruitable ones, right?