subcontracting issue in reconcilliation

Dear All,

During subcontracting process i have sent 20 components to get 20 semifinished materials

During GR if i try to post the stock with 103 and then with 105. While posting 105 if i try to expand the semifinished materials system shows the components also where system is allowing me to edit so that i can make 20 as 2 and if i post system is allowing me to post the entries

My user need to keep a tolerance for that. is that possible or there is any possibilities of totally blocking it from manually editing