I know this is very weird but here it goes:

My machine is Dell Inspirion I7 desktop and I'm curious how you'd go about installing Windows 10 or even Windows 7 32 bits WITHOUT erasing my Win 10 64 bit build? I partitioned my harddrive with like 50GB of space and named it Windows 10 32 bit for a possible future install and when you get a Windows 10 media creation tool ISO it says you cannot install from ISO message as I was going to put it all there in the new partition I made after mounting the Win 10 32 bit ISO.

If worse comes to worse I have a pre activated WIN 7 X86 ISO I have used in a VM once and could use that in leu of 10 since it's also 32 bit. Would that still result in my questions below?

I am guessing you have to format a USB drive THEN install it from there the hard way? If so will it erase my Win 10 or do I have a choice during install to choose where it goes? IE: My new partition and even furthermore will I be able to boot back into Win 10 64 bit which is my primary OS?