When I am saying:
Upon request, the homework has to be handed in to the teacher.
does this imply, that it is the teacher who is requesting? Or could it also be, say, the director?
If in the above sentence it is not necessarily the teacher, could I then express this by saying:
The homework has to be handed in to the teacher upon his/her request.
This clearly states that the teacher requests, but is this something which is said? (It sounds a bit awkward to me.)