This is a chicken and egg story. SAP is actually searching for the 543 to post reversal of the components as you are trying to post 102 on the BOM header material and given you have the item category as subcontract. Since it is not finding it throws up the error.
You have now reached a deadend, the only way forward is to manually issue the components to consumption for the missing 543 movement and accounting this transaction as an exception and move on.