While our primary ArcGIS Online Org has used SAML logins for quite some time, we've had a secondary AGOL as well as an on-prem Portal that have used ArcGIS user accounts for some time before implementing SSO on them. Thus, we have many existing ArcGIS accounts, and those have identical names to their SAML counterparts because we'd gone with a similar naming convention early on ("username_org"). So we cannot simply have existing users log into the org using their SAML account because of the conflict.
My question is this: is there any way to convert an ArcGIS Online account (or local Portal accounts) to SAML type? I'm happy to do this using Python APIs if needed (I can see no way to do this through the web interface). If not, what is the best solution? Is it better to keep the old accounts and just have new users utilize SSO, or should I try and transfer data for each user to a temporary holding account, delete the original, then transfer to the SAML login once the user has gone through SSO once? Or is there a better way I haven't considered?
I'm just curious if anyone else has gone through this before. I'm not seeing anything about it on the web or forums, though maybe I'm just looking for the wrong search terms. Thank you for any suggestions or insight!