Best Trade Solution

Below is a transaction procedure between buyer and seller

1. Both parties sign SPA
2. Seller presents proof of product
3. Buyer issues DLC MT700 to seller bank X
4. Seller ships products to buyer
5. Buyer verifies product and pay for product at full value via MT103/TT to seller bank Y after sgs at destination within 15 days.

In theory, seller can still present all the documents to seller's bank and cash out the DLC MT700 at bank X after receiving payment from buyer at bank Y, correct?

When issuing DLC MT700, will it help to avoid seller cashing out MT700 after receiving payment if buyer adds the following additional condition to field 47A

please help me with this

How would the goods on open account be received without the transport document and any other related documents that might form part of the import requirements? if such documents have already been provided to the buyer how would the seller provide the same documents under the LC, unless fraudulently?

You seem not specify what additional condition it would be.
Seller would be sued by bank. There is no way that it can cover up the scheme. Seller`s bank would get reimbursement from issuing bank. If applicant already paid seller, issuing bank would inform seller`s bank. Seller`s bank would know the truth anyway. You can`t fool the bank.