Windows 7 and Windows 10 proper UEFI dualboot method?

Hello,

I've been trying to install Windows 10 as my second OS, but it seems the installer is incapable of figuring out the correct partitioning. Here is my current windows 7 setup (no dualboot yet):

-EFI-System partition
-MSR partition
-Primairy (OS installed here)
-Primairy (partition for data, programs etc...)
-unallocated space (60gb, intended for windows 10)

Now, when I run the windows 10 setup it'll work fine until it gets to the partioning section. I create a new partition out of the unallocated space which all goes fine except for the fact that it also creates a aditional recovery partition and also an EFI-System partition! Causing me to end up with 2 duplicate EFI partitions. And if I press 'next' it'll give an error saying that it cannot find or create a system partition even though there are already 2 Efi system partitions (one from win7 and the other one that the setup created).

If I, instead of manually creating partitions, just select the 'unallocated space' and press 'next' it'll give me a warning saying that the order in which the gpt partitions are set is not recommended with the option of continueing or cancelling. If I continue, it will proceed to the install phase but will shortly generate an error msg with 'The system partition seems to be formatted as ntfs'. Even though DISKPART tells me that it is formatted as FAT32...

So i'm at a loss on how to create a dualboot setup with windows 7 already installed as an UEFI solution...

Where did you get the Windows 10 ISO from? How is the media created?

From the Seven desktop Try running as Administrator Setup.exe from the Sources folder, report back results.

Yes, I got the ISO file from the above link and used rufus tool to create a bootable USB disk out of it.
Sucks that a dualboot option isn't possible.

Also, running the SETUP.EXE as Administrator from Win7 would be useless since the Custom install option is only available if you boot into the setup instead of running it on Windows.

Thanks for helping anyways.

No, that is not correct that you only have access to Custom install from booted installer. I thought you asked here for help. I would not have suggested you try that if it wasn't a viable possibility.

So I'll repeat: you can run the Windows 10 installer from the Windows 7 desktop, mount or extract the ISO, browse to Sources folder, run Setup as Administrator. Choose Custom Install, select your target partition. Report back exact error message or behavior.

Please post back a screenshot of Disk Management - Post a Screen Capture Image.

Please also tell us what the settings in your UEFI firmware are for CSM, Legacy BIOS, UEFI, EFI and Boot Priority order.