Several VNC users on a same machine

I use tightvnc on a remote Debian 10 machine with a single user with the service configured as this :

root@actarus:/etc/systemd/system# cat vncserver\@.service
[Unit]
Description=Start TightVNC server at startup
After=syslog.target network.target

[Service]
Type=forking
User=jpc
Group=jpc
WorkingDirectory=/home/jpc

PIDFile=/home/jpc/.vnc/%H:%i.pid
ExecStartPre=-/usr/bin/vncserver -kill :%i > /dev/null 2>&1
ExecStart=/usr/bin/vncserver -geometry 1850x1000 :%i
ExecStop=/usr/bin/vncserver -kill :%i

[Install]
WantedBy=multi-user.target

That works fine for a year but now I'd need to add 2 other users and I cannot find any documentation in english or french to help me. Maybe I don't search in the right direction.
This is the reason why I come here to ask some help

Thanks

Jean-Philippe