How to create dropdowns that leave out values that are selected in previous dropdowns?

Hi!

I need to create a field mapping flow, so let’s say there are two lists:

List 1:
call_id,
user_id,
date

List 2:
callid,
user,
date_created

I want my users to connect the correct fields to eachother with dropdowns.
For a better UX, I’d like selected values not to list again in the next dropdown.

So for example:

Dropdown 1:
callid, (SELECTED)
user,
date_created

Dropdown 2:
user, (SELECTED)
date_created

Dropdown 3:
date_created

The dropdowns are created from a repeat depending on which fields are available, so this changes every time. I tried several ways to do this without any results.

Does anyone have an idea how to achieve this?