Transferring docked entities from one mothership to another mothership/station

[djthekiller]

So i have a dilemma, i wanna make a cargo ship which will:
A) unload its cargo
B) Transfer it to a station/ship
C) be able to take an empty cargo and dock it to itself

So i know that for this you will have to dock to the entity itself, maybe with a new block type such as the entity exchange rail,
you dock to this entity exchange rail, and you have a circuit of pickup rails that go between the ships when they meet, they should act as though they are one circuit
ANDDDD.... if they are over lapping then they wouldn't matter because of the no physics