I have been trying to install LibreELEC with Windows10, both on separate partitions on my laptop, but with no success.
I installed LibreELEC on my HDD, shrank the storage partition using gparted for some unallocated space. But when i tried to install Win10, the installation procedure didn't complete with an error message showing up " Windows could not prepare the computer to boot into the next phase of installation. To install Windows, restart the installation". Surprisingly, Windows was installed just fine when i deleted both LibreELEC's system and storage partitions.
I don't know where the problem lies 
but i am pretty sure Linux/Unix OSes are pretty flexible to be multi booted with Win OSes.