HCEs in Stock Acquistion

[justatester]

Company A acquires a division of Company B on June 1, 2009 through a stock deal. Both companies sponsor 401(k) plans. The division of Company B is immediately allowed to participate in Company A's plan. Company B participants can opt to rollover the assets to Company A's plan.

For 2009 HCE determination, do I need to consider prior year compensation of all of the employees of the acquired division? If top 20%, would I consider all employees of the division in 2008 or just the ones active at time of acqusition?

What if Company B did not have a retirement plan, would I need to consider prior compensation?

What if the division of Company B assets were transferred/merged into the plan-For top paid calculation, would I consider all employees of the divison sold in 2008 or only those active at time of acqusition?