I envision this working similarly to the online teacher recommendation form. Admission office would create an online release of records form for the candidate parent to provide release consent to their current school. The candidate parent would enter the email address of their contact at the current school. The contact would receive an email with the request and have the ability to upload the candidate's school records. Admission Office would then process the school records like they do a teacher recommendation form submission or test results.
We had this ability with Ravenna, and it worked well. We provided Ravenna with a list of schools and they reached out to them to set up repository accounts which allowed the schools to upload records directly through the checklist.