I vote mercanary.I think the garrison script would be messy and would take a while to do.But another thing if you do add them as mercanry how are you going to do it? I mean are you going to tie it in with a specific event?For example:
Code:
unit Crusader Sergeants exp 0 cost 210 replenish 0.15 - 0.35 max 2 initial 1 end_year 1280 religions { catholic } crusading
Or are you going to tie it in with a mission or specific event? Such as in TATW:
Code:
unit Rhovanion Mercs, exp 0 cost 780 replenish 0.02 - 0.04 max 1 initial 1 events { mission_defend_dale_success } factions { timurids }