SAP system allows user to issue over material from the vender through 542 movement type ( via MB1B Transaction) without refering to any sales documents.
It's a standard SAP functionality which you can control MB1B:
Change the IMG settings for movement type 542 and remove the transaction code MB1B as allowed transaction code. Use ME2O only. If you want to issue excess material to vendor, you will have to check 541 movements and also check batch numbers in mmbe ( Private stock in contract manufacturer and components)
MB1B Type 542 for the Movement Type and Type code of production unit
Click the enter button
Type material no, re-take quantity, unit and lot ( batch ) number Click enter button and save The lot numbers ( which you sent to the vendor and re-take from vendor) must be same Vendor means contract manufacturer