First of all, you have to add them to the corresponding faction in the EDU (export_descr_units) text file. So search for the Hysteroi Pezhetairoi and next to the last line, add: romans_julii and thrace

This seems to be it, as the Hysteroi are a mercenary unit (a trick for having 2 units sharing the same model). So no you could just try and play with them in a custom battle.

When all is satisfactory (if not say so here so I may help), go to EDB (export_descr_buildings) text file and find the Hysteroi. Copy every line with their name and paste them in the unit list of "army_barracks_J1" and "royal_barracks_J1". Oh and don't forget to replace "macedon" with "romans_julii" next to 'requires factions'.

Ta-dah! You can now recruit them where Makedonia does the AS. If you want additional regions to recruit them, copy/paste the lines of a nother unit (which can ONLY be trained in the region you wish to train the Hysteroi), change the name of the unit to "hellenistic infantry hysteroi pezhetairoi" and the ownership to { romans_julii, }.

Similiar process for Epeiros, only you have to change ownership to "thrace" and place the unit recruitment lines under army_barracks_I1 and royal_barracks_I1.

Hope this was clear. If not, I can post an example.

Maion