Win 10 upgrade on Tripple Boot Machine

I have a Dell XPS 9100 machine that is triple boot, Win 7 SP1 Drive on C (this is the OEM OS), and Win 8 (not 8.1) on Drive I, and Win XP SP3 on Drive D.
I would like to do a upgrade of the Win 7 SP1 Ultimate drive C to win 10 pro th2-10586. Can someone suggest how I might do this and keep my triple boot intact?
I have been an insider since the program started and have run win 10 pro on several VM's on my win 8 OS. I also have Two Retail win 10 pro USB drives (10240) that I'm sitting on.
Would it be better to upgrade the OEM OS or do the upgrade from one of the retail USB drives and then let it update to th2-10586?
Thanks in advance for any help.

almondman said:

I have a Dell XPS 9100 machine that is triple boot, Win 7 SP1 Drive on C (this is the OEM OS), and Win 8 (not 8.1) on Drive I, and Win XP SP3 on Drive D.
I would like to do a upgrade of the Win 7 SP1 Ultimate drive C to win 10 pro th2-10586. Can someone suggest how I might do this and keep my triple boot intact?
I have been an insider since the program started and have run win 10 pro on several VM's on my win 8 OS. I also have Two Retail win 10 pro USB drives (10240) that I'm sitting on.
Would it be better to upgrade the OEM OS or do the upgrade from one of the retail USB drives and then let it update to th2-10586?
Thanks in advance for any help.

Hi
Just last sunday i upgrade my tripple boot Win7->Win10,Winxp,OSX86
I think you better upgrade win8 instead win7. honest...
save the activation token and key later windows7 if you like to clean install again with advanced token manager by josh cell 3.5rc5.

I was tried using direct upgrade but "something happen", do this first perhaps you are lucky. and you dont need to use all the below.

I suggest you use usb upgrade Clean install using gatherostate. Look on tutorial index.
the genuineticket is used later after win10 installed.
If you use mbr try boot with mbr usb, not uefi, unless you are using gpt with uefi on.
Before upgrade/clean install, and you should know which one with partition active now using pwhe.
I booted usb win10 installer, choose the partition where i want to install, by format it first in win10 installation.
after install, you can use bcdedit or easybcd for configuration multiboot.
I suggest to pick the drive boot manually on easybcd for configuring the booting.
done.

You can download the last version ISO from Microsoft Tech Bench and use it to upgrade 7 to 10. It should not affect your other OSes. In worst case you will have to use EasyBCD to add the relevant boot entries again or reinstall Grub.

English language warning: The language descriptions on Tech Bench are rather confusing. "English" is English US while "English International" is English GB and cannot be used to upgrade Windows 7 or 8 with the English US language.

Thanks for the suggestions.