I wanted to avoid additional System partitions, so here is what i tried :
I added custom entries to clover, setting the Volume to the correct partition, and the path to "Path: \Windows\system32\winload.efi" (this is the bootloader path read by easybcd). I also added the NTFS.efi file system driver so clover can read the file out of an NTFS partition. No luck here.
Later, i tried Setting the default partition in the windows bootloader to windows 10 (with a timeout of 3 seconds, via msconfig), and then copied the EFI/Microsoft to the actual system partition where windows 10 is (copied with linux because BCD was locked in windows), and then restored back the time out to 30 seconds, just to test, later i added an entry to point on the bootloder on the windows 10 partition.
That didn't work either, because the windows bootloader settings are overridden on the EFI partition, so that was also useless.
Conclusion, windows has the worst, inflexible bootloader.
I have a feeling that even with additional EFI partitions, windows bootloader will still save its settings on the first one (after all, accodring to wikpedia windows recommends that it uses the first partition as the EFI one, so no wonder it would scan partitions until it finds the first one and dump all of its **** there).
Nonetheless, adding other "fake" FAT32 EFI patitions might work, and my try maybe didn't work because it's not on a FAT partition, as required by the UEFI specification. i didn't try this yet, i'll leave that for some other time.
Anyway, this is here, in case anyone else is doing this too, would save him some time.