This should be done at a time where no one is using the shares or are informed not to use the shares,  

since there will be a time where you are copying files, recreating the structure and users and changes made during this time will not be copied

  1. Assign yourself to all shares on the company. 
  2. Rename the old company and share to (old) this will make it easier to recognize. 
  3. Create the new company and the same shares (without old). 
  4. Assign yourself to all shares on the new company. 
  5. Install the PC client on the server, but remember you will need the space for the shares 3 times. 
  6. (You can install it on another pc, but then you will have to download and upload all the files, instead of doing it internally on the server.) 
  7. Copy the data from the old share to the new ones, one at the time. 
  8. After all the data is copied and uploaded (remember to check the queue in the client). 
  9. Create the same users as on the old company and assign them to the same shares on the new company. 
  10. If there is any groups, create them on the new company as well and assign the users to the same groups and assign the groups to the same shares on the new company. 
  11. Once all files is copied and all users, groups and shares have been recreated and assigned. 
  12. Remove the users from the old shares and remove the users from the old company.