Add Multiple shared IPs in WHM

First, you need to create a /var/cpanel/mainips/ directory, if it doesn’t exist:

mkdir /var/cpanel/mainips/

Then, create a /var/cpanel/mainips/root file, with the following content:

1.2.3.4
3.4.5.6

Basically, each line is an additional shared IP in WHM. That’s it!