Dear Qualtrics Community,
as part of a research project, I am exposing participants in a survey to one out of two possible mock-up e-commerce websites (picked through the Qualtrics block randomizer) embedded within the survey as an iframe. I have full control over the mock-up webpages since they have been created on WordPress purposely for this experiment, therefore I would have full access to the page analytics of the mock-up webpages (e.g. time spent on page, clicks, products added to cart, etc.). After interacting with the mock-up webpage, participants are asked to answer a set of questions pertaining to their experience with the website. This is basically the reason why I opted for embedding the page within an iframe rather then re-directing participants to an external webpage with a link, since I suspect that I would lose many participants if they have to come back to the survey after browsing the external webpage.
It would be fundamental, for the purposes of my research project, to keep track of the user ID on Qualtrics for each session observed on the mock-up pages. Is there any way of asking Qualtrics to pass the user ID to the mock-up webpage embedded in the iframe? Alternatively, do you have any better suggestion on how to handle this type of survey?

Many thanks