Restore from windowsimagebackup file? Win10

Hi wonderful experts,

I just increased the size of my Boot Camp partition. Before doing that, I created a "system image" in Windows 10 so I have a file called windowsimagebackup on an external drive. Then I stupidly went and booted from a USB recovery drive and did a "system repair" as per Microsoft's instructions, and *lost my Mac partition*!! Luckily the folks at Apple helped me recover it, but it was pretty tedious. So now I'm trying to find a safe way to get Windows 10 back to the way it was.

I've read the following on a Microsoft forum:

- "I redid the bootcamp partition from OSX, and when I got to point where you install Windows 7, I did the restore from image option, which I had stored on an external HDD. I was afraid it was going to overwrite the Mac partition, but it didn't." Is there a "restore from image" option in the Windows install process? And is it true that the Mac partition won't be overwritten?

- "What you want to do is make that bootcamp partition but do not install Win10 to it. If you do, you won't be able to unselect "Format partition" option. Create a boot USB drive using Media Creation Tool (see https://www.howtogeek.com/186775/how-to-download-windows-7-8-and-8.1-installatio n-media-legally/) and then boot to that (holding Option key). Then go to Troubleshoot -> System Image Restore and hook up your external drive that has the System Image you created in Windows 10 from the Backup & Recovery (Windows 7) part of the Control Panel. The "Format" option should be unselected for you and keep it that way." How do you create a Boot Camp partition without installing Windows to it? It immediately asks you for the location of a Windows ISO file. Or do you just abort the Windows setup as soon as it starts?

I have a MacBook Air 2017 running High Sierra.