Hello JABBARA,
It would like the most obvious thing to do, but I think I found the reason.
In thet CASE 1 there are two options:
1) Fuel leak stops after engine shut down
2) Fuel leak continues after engine shut down
For option 1 there is no INR TK SPLIT needed. As the engine is shut down and the fuel stopped decreasing.
For option 2 it would only make sence if the leak is in the inner side of the SPLIT. However you do not know unless you try and this takes time. The inner tank is isolated so you might just as well use as much as fuel through the engine and land than use half of it and have the other half go through the leak.
You might even try to use as much as possible from the leak side tank by feeding both engines, but for this you do need to monitor it correctly and change at least the unaffected side bk to its onside engine before the affected tank is empty.
Hope it makes a bit sence because it is nowhere written. It is just trying to put logic together.
Kind regards