Problem with Return Order - Advanced WH procedure

Meri

Dears,

I have problem with Return Order when Advanced Warehouse Procedure should be followed. The situation is the following:
First, a PO is created for Item "X" Qty 10 that should be received in WH1 (for example).
Then a Purchase Receipt is posted for all the 10 Quantity of the item in WH1 and put away doc is registered.
Then a Transfer Order is made - 5 psc of the item are transfered from WH1 to WH2.
Then is realized that the items are not as was requested and need to be returned to the vendor.
First I try to make RPO for 10 qty but the system doesn't allow to this beacause it says that I have only 5 remaining psc from the Purchase Receipt that can be returned. Other 5 psc are applied.
Then I made another TO to return the 5 psc from WH2 to WH1 beacause I thought the system will unapply the entries.
Then I deleted the first created RPO and created a new one, but the situation was same ase previous. Remaining qty was still only 5.:(
I tried to unnaply the entries through the Application Worksheet window but the system has shown message: Entries applied to an Outbound Transfer cannot be unapplied.
Now, my question is how can I manage the situation? Is there any way to unnaply the entries which I'm missing? will be right thing to put the item and Qty in the Created RPO manualy and then posted , without using Get Receipt Lines to Reverse function - what are the implications in this case ?

Thanks and Regards,