Using Windows 10 Installation on external HD as guest Operating System

I have installed Windows 10 on an external HD (SSD connected via USB C), it is bootable and I managed to use this Installation as guest operating system with parallels (I don't remember the exact version, now I am using Parallels 15, macOS Mojave 10.14.6)

Now I want to replace this disk with a bigger one.
Cloning the old disk and trying to start the old virtual machine with the old settings doesn't not word.

When I create a new virtual machine and configure the options for the hard disk I do not see the same option for the "old" bootcamp partition neither with the new or the old disk attached to my mac.

Starting up the old guest OS still works ...