First of all, sorry to use an automatic translator but, like all French, I am really bad in foreign languages!

Please note first that I searched the forum but I could not find the answer to my question.
My problem is this:
I will take for example 2 Banks of which I seek to exchange Objects of value.
Bank A is close to the airport of city A.
Bank B is away from the airport in town B.
I use an intermediate station C for transfer.
My plane loads the objects from bank A from airport A, then goes to airport C. There it transfers objects A.
A truck loads objects A from airport C and then goes to bank B.
There it unloads and then loads the B objects to transfer them to C ... And so on.
Unfortunately, when it arrives in C, it transfers the objects B and then immediately resumes them to the bank B ... And the snake bit his tail!
How can I please force my truck when it is in station C, transfer the objects from bank B and load only those from bank A which are waiting to forward them to bank B?
Same for my airplane that walks my valuables A from A to C, then A etc ... without ever unloading ...
I hope I made myself understood.
Thank you so much for your help as I am going crazy!
