Hello,
I have gone through the requirement and understand that you would like to use shared hosting provided by Milesweb. I also understand that there are 2 domains exists in godaddy. I would like to get below details inorder to assist you in a better way.
1. Are you planning to sell webhosting to your customer?
2. Do you want to handle invoice, quotes for your customer? If so, you can try out WHMCS which generally used for webhosters
I do have experience on cPanel/WHM, Centos, Ubuntu operating systems. I am available now to discuss and generally works between 9:00 AM IST to 9:00 PM IST.