Not sure if i got your idea but...
....If you mean with "3 different IDlogin then user create 3 private space" that there are 3 seperate private spaces for 3 users (one for each) i really recommend to do shared device mode using personal cloud storage.
...and regarding "and we login this ID in another device than no need to create private space", i guess it would be nice to have this user bound and if you switch the device but from security perspective i see a risk as you can't /don't want to share the security token/password/... in cloud which would be needed in order to do it (the new device would need to know it in order to be able to open the private space). So, this won't be possible i guess.
