How to create Import Declaration (Inward Processing) in SAP GTS

How to create Import declaration in SAP GTS system for transaction based on Sales Order and Return Delivery documents in ECC6 feeder system. The scenario is described as below:

In backend (feeder) system ECC6:

1. Sales Order SD Document Category = u2018C u2013 Orderu2019 will be used.

2. A Return Delivery Document similar to LR will be used (Document category u2018T u2013 Returns Delivery) to take back the material.

Import Declaration functionality system requirement is as below:

1. It should be possible to send out Pre-notification to Customs when the goods are picked up from the customer site (based on the order cerated).

2. When the return material is received (on Goods Receipt against the Return Delivery) final Import Declaration to be submitted to the customs authorities.

3. It should be possible to track (tag) if any replacement material is sent back to the customer. Meaning the Import of a return material should be tagged with corresponding export (replacement material sent to the customer) transaction.

My understanding is that the Import Declaration functionality in SAP GTS is based on Purchase Order and Shipping Notification. I would like to know how the above scenario (Sales document based) can be best supported for Import Declaration via SAP GTS system.

Thansk in advance for suggestions/ideas.

BR/Arup