Last updated: 2017-01-23
Works with CiviCRM 4.7 and should work on CiviCRM 5.0 or higher
This CiviCRM extension provides an API method that allows you to search for relationships that were active on a given date. I hope that this will be a temporary extension, and that this functionality will one day part of CiviCRM core.
For more information, see the github project page: https://github.com/Chirojeugd-Vlaanderen/relationshipsearch