Mid-Year Corporate ADP testing

[PMC]

401(k) Plan maintained by a controlled group - Employer A and Employer B. Plan year is calendar year. The was a change in ownership in October 1, 2012 to the extent A & B are no longer part of the same controlled group and they want to maintain the Plan as a multiple employer plan going forward.

Understand the transition rule for coverage but for ADP/ACP would the Plan run these tests with A & B together for 2012 plan year using contributions/compensation for B up to 10-1-12) and then do separate tests for Employer B based on comp. and contributions for October thru December 2012?