I have a dropdown where a user selects their school at the start of a survey. I have an embedded variable called CID that I pass through a URL variable. This tells us which school district is filling out the survey so like 12345 is Sample School District.

What I am trying to do is when the survey sees that CID variable it filters the list of schools in that dropdown to only show the schools for CID 12345. I have a supplemental datasource uploaded that would accomplish this (CID column and School column) but it appears I cannot do what I want using that list in Qualtrics. (Javascript is an option but it requires constantly modifying the values in the list on each survey and we have many so far less than ideal)

In poking around, it sounds like the only way to do it is to involve a web service where the survey would send that CID which the web service then sends back the school names that match the CID it receives. Does anyone have any experience with this and point me to resources or examples or share their workflow?