How to trigger secondary http in partner profile

I have an existing trading partner profile where the primary http in the delivery method has been configured to a particular URL, e.g. A, and checked as the “preferred protocol”.

Due to a new conversation script for another purpose, we need to send some other document (while old one still using A) using a new URL, e.g. B, for this same partner. How can i trigger the secondary http instead of the “preferred protocol” in this case.

My first thought was to change the service, And change the triggering B2B service in the conversation script for the “Send Document” step.

Does anyone has any experience to pin down the exact service or sub-service to modify. Appreciate any advise.