Celigo eBay to NetSuite to Shopify

Wondering if anyone has a flow for accomplishing this task?

Celigo eBay Order comes into NetSuite, then NetSuite runs a modified Order Search that pushes the Order to Shopify.

The purpose would be to take advantage of the Shopify Shipping discounts.

I have started to build a Standalone Flow for it, have built a modified Search based on the existing Search to allow for the use case. 

Just wondering the best method from that point to send to Shopify and then sync back to NetSuite so Shopify Order number generates, etc. Since the eTail Order ID is already populated from eBay - I am thinking it will create a conflict.

So would setting up a "custom" field for a second eTail Order ID be a way to do this?