I'm not sure if this is the right place to ask... but since it involves Win 10, I figured here was as good a place as any... Currently I multi boot OS's using XOSL (a hold over from long, long ago...) my setup is... Disk 0: 500gb Samsung 850 EVO SSD (XOSL Bootmanager, Win 7 64bit New, Win 10 Pro) Disk 1: 250gb Samsung 840 SSD (Win 7 64bit OLD) and various SATA and USB hard drives for storage and "work" The OS drives are done as MBR. XOSL resides in a FAT partition taking up less than 8meg space. This setup allows me to select the active partition that I want to boot from, it becomes "drive C" and gives me the option to have the other OS partitions be hidden. I have it setup that when I boot Win 10Pro, the two Win7 partitions are hidden and do not get drive letters, or when I boot Win7 New, Win10Pro and Win7 OLD get hidden and don't get drive letters, etc. Long story short this method gets me 3 independent OS partitions. I can use Acronis to backup/restore the partitions individually, without impacting anything. I can re-install Windows on one partition without impacting the other OS partitions, or boot manager. And I can selectively hide/unhide partitions when selecting a boot option so I don't end up with extra letters I don't need, and so that nothing touches the other OS partitions. If needed, XOSL can be installed/modified after the OS's have been installed. I'm now looking at upgrading my drives from MBR to GPT, but XOSL doesn't work with GPT (do to SLIC issues with MBR vs the latest 3201 bios version on my Asus Z170-Deluxe, 3007 and below are fine). I've seen talk about using window's built in boot manager/menu (and BCDEDIT to add/change), but it appears that I can't hide the extra OS partitions when not booting from them. I've also seen comments that its better to install the newest OS (i.e. Win 10) last, so I'm not sure how "independent" the partitions will be. (i.e. if I need to format "windows 7 new" and re-install, will it mess up the other partitions, or the windows boot manager?) And It looks like I might have to re-load each OS to get them on. Are there any good alternatives for GPT that works like XOSL? any easy way to switch my boot menu without having to re-install all my OS's? or am I stuck? NOTE: I'm currently running with BIOS 3007, tried upgrading to 3201, encountered the SLIC issue and have backed down to 3007, so If I keep my bios at 3007, I can keep using XOSL. I'm just thinking about the future...
I use rEFInd but it doesn't automatically hide system partitions of other OS. You can easily do that in disk management though. It is certainly independent of OS - you can put in on SD card if you want.
For converting a disk from MBR to GPT, I use a FREE utility called AOMEI Partition Assistant. It is very simple to select from the menu of options that you can do to a disk to convert. I would put one OS on Disk 0 and the other OS on Disk 1. I do this and I don't "hide" anything. I change the drive for the other OS to the Z drive or the A drive just to get it out of the way. Then I ignore it. The bigger problem is that the OS will change the security descriptors for all files on your data drives. Then you can't access them with the other OS when you boot up in the other OS. It is a pain in the ass to change the security descriptors for all your files. It can be done, but it is tedious and takes time.