Case: child being covered by two insurance companies - primary by dad, secondary by mom. Insurance companies will not process claims due to lack of information from primary for processing claims as dad isn't cooperating, leaving the secondary (mom) left holding the bill. What legally are options?

Normally, the primary insurance coverage pays and then the secondary insurance pays if the primary does not pay. Best to file with secondary insurance company and let them go after the primary insurance company. You should be able to file with the primary insurance company yourself. If none of this works, go to a lawyer.