Hmm...well, for loading more than 1 instruments, you can try this:
First, load any instrument, as usual.
Then, you are gonna click on the empty black space below the library you've just loaded, then you can load another instrument.
It should solve the problem easily, but let me know how it went, just in case, or if you need more info.
No problem, good sir!
Any other issues you are having with Kontakt?
Yeah, same for me.
There’s an option in Kontakt 7 under “manage libraries”
"Files, Libraries, Quick-Load: Double-clicking on a file replaces currently selected instrument slot"
If you untick that, adding a new instrument on your pc will always add another instrument rather than replace your existing one.
However, if you use the S series keyboards rather than your pc, and browse and then load a new kontakt instrument from the S series keyboard, it will still replace your existing one.
Not tried (away from studio at the moment so can’t check), but I suspect what’s written above would fix this, on your PC click an empty space below the instrument, then I presume using the S series to browse and load wouldn’t affect your existing one. Although to me, having to grab mouse and click on empty space when all I want to do is browse and add instruments from my S88, its what should be an unnecessary step.