Setup multiple shared IP is not possible through WHM. If you have such requirement follow the below steps to use multiple shared IP’s in your cPanel server.
1. Log in as root
2. Create a directory “mainips” in /var/cpanel/
3. Create a file “root” in the directory
4. Enter the IP’s you want to use as shared IP’s in each line
Now you will be able to use multiple IP’s as shared IP in a cpanel server.