[Seriak]

I would have the full siphon with an emergency on one end and a trickle with an emergency on the other. Not sure why this wouldn't work. For my trickle I essentially made it a durso for quiet operation.

You would not be able to tie the full siphon into the trickle, but when you needed to divert the water you could open the full siphon all the way so the trickle was no longer in use and then divert the full siphon where you need it to go. However, I am not sure if it would be a full siphon at that point unless your diverted pipe was also under water at the destination point. Can't quite picture this one in my head yet.