Merging 2 seperate papers with bibliography


Currently I’m working on my masters thesis on EndNote x3.  I wrote each chapter in a seperate word file with a seperate bibliography from one endnote library. Now I would like to merge all three docs so that the bibliography will merge in alphabetical order but I can’t figure out how this is done. Using just copy/paste doesn’t seem to do the trick and I’m worried I will have to sort the bibliography by hand. I would appreciate any help.