Open up "Mobhack OOB editor" (on the utilities tab of the game options window)
Choose the relevant OOB
Search for the unit (ie Ram I) Copy to paste buffer (button at top)
Scroll down to an empty spot (traditionally in the 900's) Paste from Buffer (button at top)
Change the data you wish (end date= Until), name, etc.
Hit Red Tick to save unit.
save tab to save OOB.
Done
