Disaggregation for testing

[Guest Sieve]

I thought I knew the answer to this, but it's different than what I think the regs dictate . . .

Two employer are members of a controlled group. They cannot qualify as SLOBs. Both participate in a 401(k) plan maintained by one of them. The match is discretionary. The Plan's partcipating employer agreement has this box checked: "Contributions made by a Participating Employer will only be allocated to Participants employed by such Participating Employer." One employer wants to provide a different discretionary match than the other.

For 401(a) testing of BRFs (the match percentages), can I disaggregate the employers by using the restructuring rules of Treas. Reg. Section 1.401(a)(4)-9© and then test the BRF & Section 410(b)? If so, how do I test ACP?