Adding 2000 to an NT 4.0 Domain

We presently have a complete NT 4.0 infrastucture of approximately 20 NT 4.0 servers across our wide area network. It is a multi master domain of NT with many trust replationships in place and working well. Financially we cannot move to a 2000 domain until next year. PDC's/BDC's must remain NT 4.0 at this time. We have an instance that a business office server must be win 2000. From what I am reading this PDC will tunnel and take over other NT 4.0 PDC's because of active directory and kerbos, it becomes the master. Can I still add this server, as a member server, and let the NT 4.0 account manager, polices, etc be administrated through the NT 4.0 PDC? I have printed all the literature I can get my hands on about migrating etc; however everyone is is putting 2000 PDC's on, but doesn't speak to keeping PDC;s/bdc's NT 4.0. What is the best solution, given I cannot give up at this time the PDC's as NT 4.0? Time is of the essence, please respond as soon as possible. THank you!!!!!!!