Need help to PROPERLY install dual boot: Windows 10 & Windows 10

I like this method and it works for me. It's clean and simple and I would have no trouble following it. But now I have you and @Kyhi giving me instructions. I guess it's either up to me to decide which guru to follow or one of you takes the point. You folks are the experts - not me. I also don't want to turn either of you off from helping me in the future by choosing the other's method to follow. Thank you both for your help! Since I don't know what @Kyhi had in store for the next steps, I think it's only fair to hear what he has to say - if he chooses to comment.

I've never used bcdboot - but I can look it up with its' arguments to see what it does. That way, I learn something which is my ultimate goal.

When I use "Quote," do I write my comments before the quote, after the quote and/or in the middle of the quote? My understanding is that they won't be visible if I type them in the wrong place.

Are either of you familiar with migrating working apps from one OS to the other?

You normally quote the post, then reply to it below the quote.

The first big step is to remove the active tag from the partition on disk 1. Have you accomplished that? The reason that is important is so that during the clean install of Windows 10 it greatly reduces the possibility of Windows setup putting the boot files on disk 1 instead of disk 0. (assuming you don't want to get inside the computer and unplug disk 1 for the install).

Here's the differences between letting setup do a standard clean install, and using the dism /apply-image method:

Using dism, the user has 100% control over what partitions get created on the drive, where on the drive they get created, and what size the partitions are. If you let setup do it, as long as the drive is wiped clean before the install, you can fairly well predict what setup is going to create, but you don't have much choice in it to start with (though you can change some things after install).

If you have multiple drives connected (which you have two), and you let setup.exe install Windows, there is a chance it is going to put the boot files on the wrong drive. You can minimize this, especially on a legacy BIOS computer, by not having any active partitions on the other drives. Then in 99% likelihood setup is going to put the boot files on the drive the computer is/was set to boot from first which, on your computer, looks like drive 0. Of course you can 100% ensure the boot files get put on the same drive as the OS by having all extra drives unplugged during the install. Using the dism /apply-image procedure, the user specifies exactly where the boot files go. If setup.exe does put the boot files on the wrong physical drive, it's pretty easy to fix.

Sometimes setup.exe errors out on some computers before the first reboot. dism /apply-image has worked, sometimes, in such cases to get past that.

dism /apply-image works very well for adding a second OS after the first OS is already installed. In your case, we want to get a nice, clean, first install of Windows 10 going. I believe that in your situation @Kyhi will agree - remove the active tag from the partition on disk 1, boot from a standard Windows 10 USB flash drive, select the custom install option, on the next screen delete every partition on disk 0 (be careful not to delete disk 1!), select the unallocated space on disk 0 to install to, and click next to let Windows set up a standard Windows drive layout. Then, if you are going to restore your previous Windows as dual booting, all you have to do is shrink the OS partition that will get created to make room for it. <- that last step is the only real thing that will be avoided by using dism /apply-image to set up the first Windows install, you won't have to shrink the partition to make room for the second OS.

Thank you for the explanation - now I understand and will go with your recommendations going forward. I have a flash drive already to go with the FCU on it. I plan to use almost have the remaining Disk 0 for the old installation. On both installations, I have far more space than I need - so, if I need more in the future, I can shrink whatever partition I'm comfortable with. The only possible glitch I see I could run into is if both of my two images of Drive 0 get screwed up. Not likely since I always keep two images (even of Drive 1). But if I lost those images for some reason, I would never get my PC back to where it was. That's a small chance which I will take.

What is your opinion of a partial migration of apps to the new installation? I have over 100 apps and I'd like to save some effort if I can - but not at the expense of a quality clean installation. Of course, I don't need all those apps and would probably just install them as needed - or when I just have some spare time. I already have a list of 'must haves.'

I would not attempt to transfer apps from the old Windows to the new install. I would reinstall them from scratch. If you can figure out where they keep their settings, you might be able to import settings. For example, Kodi media player on my computers always stores all the media info in C:\Users\John\AppDate\Roaming\Kodi. So I always restore those settings after I install Kodi from scratch.

There are programs designed specifically to transfer apps and programs from one install of Windows to another and some people report some degree of success with them.

Also, what I would do is get a good clean install of Windows going. Make sure Windows Update is running good. Install your essential apps and programs. Get a good base install running. Then make an image of it! That way if something corrupts it again you have a good base image to just restore and save you time and effort.

Thank you. Based on your recommendation, I won't plan on migrating apps. But that's one of the reasons I want to keep the old Windows 10 (the one I'm using now) so I can refer to my current settings. When I'm done with the old W10, I plan to get rid of it.

Thanks for the support!

Hello folks! Also to @NavyLCDR: Being a holiday week, my wife needs a lot of help - so I won't be able to do any more with my computer until next week. I'll post back then. Thank you!