If you want to add more than one IP to your server, this can easily be achieved in ClusterCS following this guide:
Header over to:
Servers> Manage > Scroll-down Manage Networks >
Add New Network> Servers IP > Attach to network > Select your newly added network > fill with IP’s details.
Once you are done adding and selecting your new IP, hit Save
You can now select the newly added interface/ IP by heading over to the Network page:
You can now Run the setup and the newly added interface will be available on your server!