Using Endnote with Non-imported Word Reference Set

I have a book’s reference section in Word that includes over 1,000 references – too extensive to import into Endnote using any of available methods mentioned previously in this forum. When revising the book, is there any way I can use cite while you write, and later integrate the new refs that Endnote X3 produces into my existing Word reference set, using Word’s alphabetizing function? Thanks for your help.