O2 and H2 Tanks Should have a Source button/function

In Space Engineers there seems to be a feature that was overlooked. It is my opinion that the Tanks in the game should have a reverse option to the stockpile or a way to choose what sources it can receive from. There are 2 possible solutions I can see for this particular problem:

1) Make a series of toggles in the menu of any Tank block that tell it where it can receive its gasses from. This would look like a button for vents and a button for generators. To me this seems like the lesser of the 2 options.

2) Add a Slave button to the tanks. This button would be the absolute opposite of the Stockpile button. For example while the Slave button was toggled on it would force the tank to push out all of its contents to other Tanks but not trigger any resource generating blocks like an O2/H2 Generator. It should also allow it to only receive any gas into its tank if the other tanks on the system are full.

In conclusion I believe this addition to the game would make managing airlocks among other things a bit more efficient. For a practical example lets assume I have a small scout ship. It is designed with 1 O2/H2 Generator 1 O2 Tank set with Slave and Stockpile off and 1 O2 Tank with only the Slave option toggled. My airlock would pull the air out of the room and place it in the non-Slave O2 Tank first and then would input the rest into the Slave O2 Tank. When the room is pressurized again the Non-Slave Tank would be pulled from first then the Slave Tank would attempt to fill the Non-Slave up as if it was an O2/H2 Generator from its reserves. When the Slave Tank is empty if the Non-Slave still needed to be filled then the O2/H2 Generator would kick on and fill it back to max capacity.