I tried my own method. Its a bit intrusive though.
- Normal method of placing wye/water supply BUT
- Only the FF who set up the supply/wye/extension can remove it
- If you select the wrong FF, the game will script the right one for you
- The problem lies here. It isn't obvious that another FF has been selected, so he may be in the middle of doing something else important when you send him to remove the thing
- Also, the FF would have to be on the map in the first place. Can't send him away otherwise -GAME CRASH-
I'd suggest going back to the original way, and then adding the ChangePrototype line in the appropriate places. Other than the invisible firehose, I've never run in to any issues.