Plan Document adoption

[cdavis25]

Company A adopted a 401(k) Plan on a standardized prototype document in 2002. They are part of a control group with company B. So, my understanding is B is in the Plan even if they don't formally adopt the Plan b/c it is a standardized prototype document. Roll forward to 2010. They restate the document on a VS document. Company B does not formally re-adopt the Plan; however, they never discontinued or revoked participation in the Plan either. Are they in the Plan or not? If not, would they need to do VCP or could they use SCP?