5 C.F.R. § 875.208
May I apply as a qualified relative if the person on whom I am basing my eligibility status has died?
You may not apply as a qualified relative if the workforce member on whom you are basing your qualified relative status died prior to the time you apply for coverage, unless you are receiving a survivor annuity as the spouse or an insurable interest annuity as the domestic partner of a deceased workforce member. In this case, your adult children and your current spouse or domestic partner are also considered to be qualified relatives.