allow screen to support sharing
#>sudo chmod u+s /usr/bin/screen
#>sudo chmod 755 /var/run/screen

set a guest user account in the host machine

screen -S pair
Ctrl-a :multiuser on
Ctrl-a :acladd guest
vim

the remote user logs in as guest

ssh guest@your_accessible_ip
screen -x local_user/pair  (where local_user is your local account running screen)