Cannot nominate alternative beneficiary

Why am I not able to nominate an alternative beneficiary (in the event that my primary beneficiary dies simultaneously to me)? If my nominated beneficiary dies with me, the life insurance I have with Discovery goes into my estate. I do not want this! I am able to nominate an alternative beneficiary for the life insurance I have with a different company, so there is no legal issue preventing this. My beneficiary is my husband. We both do not work and travel extensively for long distances. It is probable that we could die together. I want to nominate a beneficiary that would inherit my life insurance in an event like this. How hard can this be?