This tutorial shows you how to install PHP 5.6.x and PHP 7.0.x side by side on Ubuntu 14.04 with Virtualmin using FCGI and assumes that you already have Virtualmin configured on a server. Please read through this entire tutorial before starting.
Note: As always backup your servers or sites. I accept no liability for loss of data, problems, or damage caused to your server by following this tutorial. This worked for me but – use at your own risk.