Not a bad idea, at all - glad to...
From this DAN Overview of coverage - Top or Preferred Plan ONLY:
http://www.diversalertnetwork.org/insurance/compare.asp
Diving Vacation Interruption: $5,000 Lifetime Max: Coverage for losses incurred for dive trip interrupted due to injury or i[COLOR="purple[B]"]llness [/B][/COLOR]after departure.
$250 deductible
Diving Vacation Cancellation: $10,000 Lifetime Max: Coverage for losses for dive trip canceled due to injury
or illness before departure.
$250 deductible
Medical Non-Dive Accident Coverage: $10,000 Lifetime Max: For eligible charges for treatment of non-diving accidents outside home country.
$250 deductible
No coverage mentioned for Illness other than Trip Interruption or Cancellation above
No other mention of "illness" on the page, except for Decompression Illness
Additionally,
from DAN FAQ on Preferred plan:
"Will these benefits pay for a trip that I cancel because of my work schedule or illness to a family member?
No, these benefits are only activated if the insured diver is the one who is [COLOR="purple[B]"]sick [/COLOR]or injured in a such a manner that it would prevent him from diving
From the "Cover You Butt Dept" - buy trip insurnace before leaving the US.