“To become a MEWA, a plan needs only to cover employees of two or more employers. Because intent is irrelevant, an employer can find itself inadvertently creating a MEWA if it allows employees of other employers or nonemployees to participate in its welfare plan…. Once a MEWA, a plan can face penalties of more than $1,500/day for failing to timely file the DOL’s Form M-1, regardless of whether the plan administrator was aware of the requirement.”  Fox Rothschild LLP