Contract term research for South Korea

Story: In an agency contract, we authorized a company,named AAA Company registered in South Korea, as our sales agent in South Korea. The agent signed a sales contract with final buyer BBB Company as a seller , without the name of us. Then the agent send an Appendix attached to us. Question: 1. If we sign the Appendix, does it mean we become the seller of the contract number.M 130312FeSi STD ? 2. If AAA Company does not pay us after the company receives payment from the buyer for the contract number. M 130312FeSi STD, what legal action we can take? 3. Can we ask the buyer of the contract number M 130312FeSi STD pay us directly? 4. How does South Korea law protect "unnamed agency"? 5. Draft a full text contract for this purpose