You can add more shared IPs by following the steps shown below.
cd /var/cpanel/mainipsIf there is no such directory, create it.
mkdir -p /var/cpanel/mainips
vi /var/cpanel/mainips/rootAdd the current main shared IP and the secondary ip.
cat /var/cpanel/mainips/root 220.127.116.11 18.104.22.168Go to WHM » IP Functions » Show/Edit Reserved IPs
You can see the status of new IPs as 'Main/shared IP for root'.
That's it :)