What Do Participating Employers Do if the MEWA Does not File a Form 5500?

Hello, 

I have a few clients who are participating employers of H&W MEWAs. The MEWAs hold trusts but for reasons unknown, they  are not filing Form 5500s. Do the participating employers file 5500s for themselves, and if yes, do they file as a trust even though they are not the Plan Administrator of a trust but sent funds to a trust? 

Have the MEWAs filed M-!s?????????

We have been told yes but when I looked, I could not find any details on the DOL Form M1 look up. Seems that the MEWA are considering themselves as Non-ERISA Plans. I cannot say for certain, but my guess is that they are considering themselves as funding mechanisms and not employers. I instructed the groups to seek the advice of an ERISA attorney. Conservatively I think that they need to file as single employers. I still question though since funds were sent, and the clients don't administer the plan.