Switching from RWA to RWA for SAML re-prompts end user for MFA

Hello,

We have two Regular Web Application (RWA) clients. The first grants access to our application using the Auth0 SDK, etc. The second is used as a SAML identity provider, as documented here.

In our application, auth’d via the first RWA, we have links to a third-party app that uses the second RWA as the SAML IdP. When are users click on such a link, they are sent back to our tenant’s authentication domain and prompted for multifactor authentication. In sum, the current user flow is:

  1. Go to our application URL (app.example.com).
  2. Get redirected to our Auth0 custom domain (auth.example.com).
  3. Log in, complete multifactor authentication.
  4. Get redirected back to our app (app.example.com).
  5. Click on a link for the third-party app, for which we also have a custom domain (third-party.example.com)
  6. Get redirected back to auth.example.com.
  7. Get prompted for MFA.
  8. Get redirected to third-party.example.com

We’d like to avoid step 7. I’m having trouble understanding how an Auth0 session is used to grant access to our different RWAs in this case. From what I can see, the RWAs differ only in the allowed callback URLs (the second specifies third-party.example.com as a callback). How can we go about this? For management reasons, we’d prefer to keep our setup with two RWAs if possible, but the priority is removing the re-prompt for MFA to the end user.

Thanks in advance for all help and advice!