Is there a way to keep the list of products constant if any of them appear in the final step of the funnel or across the funnel?
user might add or remove some of the products in between.
the conversion event has product Items property which is a list with one or more products in it. I want to consider all the conversions where the the product ID from the first step is present.
so holding the first event property I guess thats when the conversation starts should work. perhaps you ant to flag the first event of the conversation with another property, say first message, and that one hold it. Just thinking out loud
I had this problem in the past as well. We solved it by always tracking ID properties as "IDs" - so in your case "Product IDs" across all events" even though with some events there, the property might have only 1 value.