Shared folder not visible for existing users

I have installed jupyterhub in linux servers and I have successfully logged in with all users available and everything seems to work fine. Now I have a new requirement where users have to be able to share their files/notebooks with other users.

So I have created a group with all jupyterhub users and created permissions and as suggested here in docs I have created symbolic link and tested with new user. After logging in with new user credentials I am able to see shared folder but unable to see shared folder for already existing users. How to enable this to existing users as well.