Unchanged. At the back, as all units that we don't sort. We could define a position for them if you suggest one / want to make a point, but very likely the current is fine right.

Assuming you had ten healers, where would they be?

WELSBY, D. 1996. screenshots below:  

All illustrations depict the same event: Sanghamitta's arrival in Sri Lanka and the transport of the Bodhi Tree. This is a myth that is still very important today for some people, so one should not expect the illustrations to accurately represent historical reality. It should also be remembered that these representations have a nationalistic character. Sri Lanka is divided into two populations that are in conflict, one Buddhist and the other Hindu or Muslim.  There is a Sinhalese artist called Prasanna Weerakkody who made some historical illustrations, some of them have been used already by 0AD team to modelize the ships.  However, you should note that the event from Sri Lanka are not connected to the Mauryan empire:

Assuming we always prefer ranged units behind melee in the poll above. Below a formation with Cavarly first then Infantry, you can see Ranged Cavalry will still be behind melee Infantry.