Issuance limits for Local L/C (Purchase Confirmation) by raw material for products with mixed export and domestic sales

Our company has a ratio of 30% export to 70% domestic sales, meaning domestic sales are higher. For example, if we export 30 units of product A and sell 70 units domestically, product A is manufactured using raw material 'a' from supplier A, raw material 'b' from supplier B, and raw material 'c' from supplier C. According to the BOM for product A, the materials are a, b, and c. 1. I understand that we can issue a Purchase Confirmation for 30 units based on an export contract for 30 units; is this correct? 2. I understand that a Purchase Confirmation can also be issued using a PO instead of an export contract; is this correct? 3. Based on an export contract for 30 units, can we issue a Purchase Confirmation of 30 units to each of suppliers a, b, and c? If so, it seems we could receive a total of 90 units worth of raw materials. 4. According to question 3, if we receive a Purchase Confirmation for 30 units of raw material 'a' from supplier A, it would be used for both manufacturing product A for export and for domestic sales, making it impossible to distinguish between them. I would like to inquire if it is possible to issue a Purchase Confirmation using the method described above.