Permissive disaggregation and ineligible employees

[t.haley]

Employer A has a 401k plan.  The plan's eligibility provisions exclude employees of Related Employers.  Employer B purchases Employer A resulting in A and B in a controlled group.  A's 401k plan is not immediately terminated (plan still has assets that have not been distributed).  When performing coverage testing for A's 401k plan for the plan year after the transaction, the plan would like to exclude Employer B's employees from testing.  Under the IRS general rule (all employees of all employers in a controlled group must be included in testing), B's employees should be included in the testing.  A did not elect to include the 410(b)(6) transition period in 401k plan.  A would like to use permissive disaggregation to put separate out employees (specifically B's employee) that are not 21 and do not have 1 year of service (the 401k plan's eligibility provisions are more lenient - age 18 and 3 months of service).  Can A use permissive disaggregation as to B's employees if B's employees are not eligible to participate in the 401k plan in the first place?  Doesn't permissive disaggregation assume that the pool of employees are eligible employees?