Yes,
DCL would be the one you would call if you booked directly with them. If the cost of your airline tickets was factored into the insurance policy it should be covered.
Not knowing which policy you purchased I pulled this from Access America's website under their Navigator Comprehensive Policy. It is the definition of family member.
Family Member means Your spouse; parent; child(ren), including children who are, or are in the process of becoming, adopted; sibling; grandparent or grandchild(ren); step-parent; step-child; or step-sibling; in-laws (parent, son, daughter, brother or sister); aunt; uncle; niece; nephew; legal guardian; ward; or business partner; whether or not they travel with You.
A. TRIP CANCELLATION AND INTERRUPTION PROTECTION*
Trip Cancellation coverage provides benefits for loss(es) You incur for Trips cancelled up to the time and date of departure. Trip Interruption coverage provides benefits for loss(es) You incur for Trips that are interrupted or delayed after the time and date of departure.
Any serious Injury or any unforeseen serious medical condition:
Occurring to You or a Traveling Companion, which is so disabling as to cause a reasonable person to delay, cancel, or interrupt their Trip;
Occurring to a Family Member that is considered life threatening or requiring hospitalization; or
Occurring to a Family Member requiring Your care.
For Trip Cancellation benefits, an actual examination by a licensed Physician must take place within 72 hours of the cancellation. For Trip Interruption benefits, this examination must take place during Your Trip. The Physician may not be a member of Your or Your Traveling Companion's immediate family or yourself, or an immediate family member of the person whose condition caused the cancellation or interruption.
Your death.
Good luck. Mary