i purchased bs knees, axxe guitars, vintage keys, phat analogue, and one of the bass ones. I want to load them all at the same time without overwrtitting the whole original es library..is that possible?

you will need to use the studio manager and voice editor.
but you only have 3 users banks to load the purchased voices into.
so you wont have room to load all banks at the one time
however you can load them one at a time and pick out the favourite voices and collate them in the 3 user banks, then save them to new banks for reloading.
You need to do a bit of copy / pasting and moving around but it can be done.
You will find when you load these banks they will automatically load to user bank 1 or 2 or 3 etc, but you then move them, remove them etc

The three user banks in the Rack are just copies of the six preset banks, which are fixed and will always be there.

The voice banks you have will not use all 384 user voices (or I’d be surprised!), so as mentioned above you need to pick your favourites from each and merge them into the 384 slots that you have.

Yamaha’s studio manager will allow you to do this, but if I may suggest it, you may like to check out my motif.factory librarian. IMHO (but I am biased!) using this is much easier, and gives you other features such as bulk import/export of performances and multis that Yamaha’s editor doesn’t provide. Check out http://www.xfactory-librarians.co.uk