Creating a new category tree

Creating a new category tree

Hi,
 
We have had ServiceDesk for a while now and we have dicided to change the category structure totally. Have you have any customer who have done this and what is best practise? I mean is it best to just create the new structure and leave the old request with the old categorys? Or will the old requests categorys disapear? Or do we have to re-categorize all old request? many questions :)
 

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