Automatically pair up respondents with contact list that drops people already paired

Hello!
I am totally new to using the Qualtrics API but think it might be what I need for my current issue.
Here's what I'm trying to do:
-I will be recruiting survey participants to my Qualtrics survey. As they come to the survey, I want to pair each of them up with a participant from an existing pre-loaded contact list.
-I can't have multiple people finish the survey and be paired with the same respondent from the pre-loaded list, but I also want to re-use respondents from the pre-loaded list if the new survey respondents matched to them don't complete the survey.
-In other words, I would like to delete contacts from the pre-loaded contact list once they've been paired with a new respondent, but then I'd like to add them back to the possible match pool if that new respondent doesn't actually finish the survey.
-Given all of that, it seems to me that it would be ideal to always match a new respondent with the pre-loaded contact with ExternalDataReference = 1. Once they're paired, I delete that contact from the contact list and subtract 1 from each contact's ExternalDataReference, so a new respondent is now at spot 1 in the contact list. Then, I would somehow need to add that respondent back to the contact list, either at the front or the end of the line, if their paired new respondent didn't finish the survey.
Does this sound possible? I'm not sure if there's an available way to reduce all contacts' ExternalDataReference by 1 at the same time, or if there's a better way to do this.
Thank you!