Change in pan

Dear Sirs,

My friend is a Partner in a FIRM having other 3 partners. The Firm is doing Business and has a  valid PAN. Now they have decided to admit 3 more partners. Whether the earlier PAN will be cancelled and a new one need to be obtained after the admission of 3  new partners. How it will affect the earlier business.If a new PAN is issued whether business continuity will bw hampered - in the case of TDS by Customers, TDS Return , Banking transaction etc. Awaiting for  reply.