Dear Bruna,
This can be done using GATP EDQA.
Check with your GATP Consultant. As on when the Stock changes happen in ECC, EDQA will be triggered.
Configure EDQA Rules in such a way that it will restrict the specific storage location stocks.
You may require to create a custom ATP category and assign these stocks to the custom ATP category AND dont include the custom ATP category in your APO Stock Category group.
Just my thoughts
Regards
Vinoth