How do i make Gnu/Screen multi-user

Follow instructions here

sudo chmod +s /usr/bin/screen # Make screen suid root
sudo chmod 755 /var/run/screen # Make the screen dir more open “Note that if you want to share a screen between two sessions of the same user on a system you can skip this step entirely. This is useful for example if you have a shared login on a system.”
screen -d -m -S multi
:multiuser on
:acladd
-You can save yourself some time by putting these commands in the .screenrc configuration file.