Use case to use one Google oauth service for multiple apps

Hi,
Does any one has use case to use one google oauth service for multiple apps? I have situation where I have multiple apps such as

  1. spl.com
  2. spn.spl.com
  3. sph.spl.com
  4. spa.spl.com

Right now I am using the different google auth services for each site because I have to provide the separate redirect url for each app.

Current flow:

  1. spl.com -> google sign -> post request to df/api/user/session?service=googleoauthspl
  2. spn.spl.com -> google sign -> post request to df/api/user/session?service=googleoauthspn
  3. sph.spl.com -> google sign -> post request to df/api/user/session?service=googleoauthsph

New flow:

  1. spl.com -> google sign -> post request to df/api/user/session?service=googleoauthspl -> spl.com
  2. spn.spl.com -> google sign -> post request to df/api/user/session?service=googleoauthspl -> spn.spl.com
  3. sph.spl.com -> google sign -> post request to df/api/user/session?service=googleoauthspl -> sph.spl.com

Is there any use case in our community to achieve this flow?

Thanks,
Sree