What should we do if we can not fullfill TO qty ?

Hi all

     We use ECC 6.0 and just use SAP WM

     We have case like this : We use reservation MB21 and then MIGO ( Good Issue ) to create TR, let just say we create reservation and then TR for article A with qty 5 EA. Then we create TO ( LT04 ) but somehow in WH only 3EA can be confirmed.

     I know we can create another TO for 2EA but the case is there are no more stock in WH. With MIGO the IM stock already GI'ed and in the WM we still need to GI another 2EA.

     Already tried to change TR but system not allowed. What should we do ? What we want is to cancel 2EA in the IM and then scrap 2 EA or just GI to costcenter.

Thanks and Regards