For an unmarried 25 year old is secondary insurance available to cover the 20 percent not covered by group policy?

In most cases, secondary insurance is not available to unmarried individuals to cover their out-of-pocket medical expenses beyond what may not be covered by an employer-provided group health insurance policy. Secondary insurance, also known as supplemental insurance, usually requires evidence of primary group coverage through an employer or government healthcare program to act as the first payer of health bills, which is not applicable in this specific scenario