A control found on certain large organs (albeit rarely) is the Pedal Separation (Pedal Divide) coupler.
This device allows sounds played on the pedalboard in passages for double pedal to be split, so that the lower half (played by the left foot) plays stops of the Pedal division and the upper half (played by the right foot) plays stops from one or more of the manual divisions by means of coupling.
Basically, this coupler is wired to silence the Pedal stops above the split point and silence the coupled manual stops below the split point; the choice of manual(s) stops is, of course, at the discretion of the performer and controlled by separate manual to pedal couplers.
Often the split point is adjustable and needs to be near the low middle compass of the pedalboard (B, c, c#, d, or d#) to permit the feet to play at opposite ends above and below the split point (photo) with the divide favoring a wider compass for the right foot which carries the melodic line; the split point should default at note 12 (low B).
A button is often located to be used as a "set button" for the Pedal Separation; the organist simply holds down the pedal key, presses the button, and a new split point is set; below the new split point would be all Pedal stops and couplers, and above it would be whatever stops are coupled from the manual(s).
This allows 4 different tone colors or sounds to be played at once without thumbing down across manuals [See blog, Thumbing Down] -- one in the right hand, one in the left hand, one in the right foot, and one in the left foot.
The instruments at Gloucester Cathedral, Truro Cathedral, and Ripon Cathedral in England are all equipped with this coupler, and there are several examples from American organ building including the Wanamaker Grand Court organ in Philadelphia and the historic organ of the Scottish Rite Cathedral in Saint Louis [See menu bar, Photo Album I].