I am friends with my insurance agent. He told me if it is not discovered that he has cf withen the first year of paying on the policy, i had nothing to worry about. I am not sure this could be as easy for an adult though. We took out a very small policy on both our children when they were born. My son was disgnoised 3 years ago when he was 13, and i decided to take out an additional policy since rates go up the older you get, and cf will make rhem even higher.
we did not disclose his cf, didn't need a physical, and waited out the first year. It may seem a little sneaky, but i did what i had to do.
all my agent did say was that as long as he didn't pass away withen that first year, the company would honor the policy.
good luck