Help please SMS thread issue!!!

[WPCentral Question]

okay so I was unlinking various contacts just using hotmail and gmail account not facebook because I didn't understand why some of my contacts were linked to 3 hotmail contacts which were identical, and now when I text off my existing text thread for a contact the reply shows up in a new thread it created. any clue how to fix this? I even deleted contacts and re put them in. The contact info on each thread is identical so why aren't they merging???? It's really frustrating because I don't want to lose all the old texts yet i don't want to have two threads for the same person.