Create a new folder in the root of the data partition being used, if any, and call it something like Hyper-V-2018.
Copy the VHDX file(s) from their current location to that (assuming there is enough space to do so).
Run the following in an elevated PowerShell where X is the destination partition:
Set-VMHost -VirtualHardDiskPath "X:\Hyper-V-2018\Virtual Hard Disks" –VirtualMachinePath "X:\Hyper-V-2018"
Get-VMHost | fl VirtualHardDiskPath,VirtualMachinePath
Create a new VM and configure its settings using the existing OS VHDX. After that is complete, open the VM's properties and add the second VHDX if it exists.
Try and start the VM. If it starts, it will require some tweaking at the network level as the vNIC's GUID and MAC will be different.