We are always helpful and informative. 

At the beginning and the end of the year, the partnership still has 3 partners, so it does not need a new EIN. You will need to allocate the part year income for the new and exiting partners so that they properly reflect their proportionate share of income. There will be 4 K-1's and one will be marked final. 

You can get a bit more info from this recent thread https://proconnect.intuit.com/community/proseries-discussions/discussion/re-sale-of-partnership-to-a...