Multiple (not multi) Employer Plan Question

[Guest ERISAcatNraleigh]

Plan says that each participating ER contributes only amounts attributable to its EEs. But the Plan was established in 1970, so (according to 413©(4)) 412 is applied as if all participants are employed by a single employer.

Plan says that each participating ER that withdraws from the plan shall contribute an amount to fully fund with respect to participants who are its EEs.

1) Is one participating ER responsible (maybe pro rata) for the contributions of another if the other defaults (due to bankruptcy or other)?

2) Same as #1, but the participating ER has terminated participation in the plan.

3) What PBGC filings are involved/required for the plan (or a participating ER) when an ER terminates participation in the plan?

Thanks for your time.