Can i format 1 os while keeping the other as it is

[pvpritiv]

 

[BufferUpchuck]

need more details about what you want.

i'll guess...
I haven't done much of this, so this is just some basic info:
you can use a partition manager software to "split" partition, so can add another OS in new partition.
aka "multiboot". this is common topic with linux. ubuntu, pclos, slax, mint, etc, most commonly installs "grub" (or other boot loader).