Assuming Client pushes you about the Crummey Letters, and upon learning of the Crummey requirement and consequences of not filing a Crummey Letter asks you to back date Crummey Letters for each of the past 10 years, especially since your firm should have informed client of this requirement a long time ago. At this point in time, you should:

1. Politely tell the Client that you cannot do that and leave it at that
2. Politely tell the Client that you cannot do that and then report Clients actions to the IRS
3. Politely tell the Client that you cannot do that and demand from you supervisor that you drop the Client to avoid potential liability
4. Prepare back dated Crummey Letters because you know that Client would have prepared the Crummey Letters if they had known of the requirement
5. Drop the client because of a conflict of interest.