How to get the Conversion Summary when using an external checkout?

[BobSmitheronni]

We have a couple of clients that are using external checkout pages such as One Click Upsell, Carthook, Intercart, etc. Although the checkouts themselves are working well they do not pass back the Conversion Summary into the order when the order is created because the checkout is not done through Shopify.

Do you know of any way to either pass the UTMs through to the Conversion Summary OR match up the customer ID or tokens to the customer so that their Conversion Summary can be attached to the orders after it is created by the external checkouts?

Thanks! 🙂