Correcting Failure to Adopt Plan as a Participating Employer

[Madison71]

Company sponsors a 401(k) Plan. Last year, two related employers began participating in this Plan with their employees contributing. The Plan document does not indicate that they are part of a controlled group of companies and does not have participating agreements or corporate resolutions signed indicating participation in this Plan. Company wants to correct and file under EPCRS to be sure it is properly corrected. A retroactive amendment to the date of participation and adding them also as members of a controlled group is going to be the recommended correction. In looking at the Forms 14568, I'm not sure what schedule they should be using. I'm thinking 14568-B, Schedule 2 - Nonamender Failures (other than those to which Schedule I applies). Also, is there a reduced fee or is it the standard fee in Rev. Proc 2013-12?

Thank you very much for your time.