Controlled Group w Different Entry Dates

A client just purchased/re-organized various companies so that we now have a controlled group due to family attribution.

                              Company A&B                   Company C

Dad                       51%                                    100%

 Son                      49%

 Currently we have three different plans with different entry dates, all are safe harbor match plans.

A--after 3 months immediate entry at the beginning of the month.

B—immediately upon hire

C--1 year, due entry 

 All companies have roughly the same number of employees—5 to 10.

The client is resisting one plan document with the same entry date for all participants.

 Won’t the different entry dates most likely cause testing to fail?  Which tests will most likely fail? 

 Am I required to have only one plan document?

Thanks