Windows10/Debian boot

I have a PC with two primary partitions (ntfs, system and recovery; windows 10 installed), and an extended partition with three logical partitions (ext4 /, swap, ext4 /var; Debian Jessie installed).

1) Using EasyBCD2.3 (community) from Windows 10 I can get to the point where I can boot windows 10 , but trying to boot Debian just freezes the PC with cursor blinking ...
2) With Grub2 from Debian I can come to the point where Debian is booting OK, but Windows isn't.

Debian sees windows partitions as /dev/sda1 and /dev/sda2 and Linux partition as /dev/sda5 (root / ), /dev/sda6 (swap) and /dev/sda7 (/var).
Super Grub2 disk recognizes the windows boot partition as hd1, msdos1 (system), and the linux boot partition (/) as hd1, msdos5.

No matter what I do on the Debian side or what I do from the Windows side, I can boot only one OS or the other. However I can boot both both systems with Super Grub2 disk (but that's not good even as a workaround).

Things are further complicated with tons of contradicting, sometime evidently false information on the web, so as relative newcomer to this dual boot world I am completely lost!

So (of course), I'd appreciate some help.
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