Toggable fuel drain switch

[kcs123]

Maybe someone already suggested, but I didn't find in quick search trough links/threads.

Can engines have toggable fuel drain switch ? For example, jet engines have this:

Quote

resourceFlowMode = STAGE_PRIORITY_FLOW

That allows balanced drain from all fuel tanks. But it is not always desireable option. Sometimes I might want for jets to drain fuel only from first stage. Jets are efficient on thick atmosphere, so could bring rocket to above 10km and drop that stage. Only after that rocket engines are fired when there is less aerodynamic forces to destroy craft.

Another example is oposite, I want to create spaceplane based on nuclear engine that drains fuel unbalanced from first fuel tank that is attached to, but for space plane eaqual balanced fuel drain is preferable to maintain center of thrust and center of mass aligned.

Edited February 6, 2016 by kcs123
changed title to better fit topic