Safe harbor wait and see approach with coverage issue

[Guest matt2800]

Plan is a temp agency excluding employees who work off site for recipient employers exclusively (all NHCEs) and has a SH 3% non-elective and has passed coverage using average benefits test for past 3 years. Looks like 2011 will be a close call on 401(k) coverage to pass the average benefits test.

If I put in a safe harbor 3% using the wait and see approach for 2011 and the plan fails 401(k) coverage, would it be ok to do a 401(a)(4)-11(g) amendment to include enough of the excluded employees by providing them a QNEC equal to the NHC ADP% to permit the plan to pass coverage and then make the safe harbor contribution. I assume I would have to make the sh contribution for the employees I added to the Plan via 401(a)(4)-11(g).