If you’re a federal employee, you will need to fill out the form sf1152 to designate a beneficiary for any upaid compensation. Your HR may have had your fill out this form as a new hire. I recommend going through your electronic OPF and seeing if you have this form on file. I have included the link to the form below. You may want to google the link if some time has passed to make sure you are getting the latest version of the form. Even if you have been a federal/government employee for several years, I encourage you to take a look to see if you have this form on file and that it has your correct desired beneficiary listed.

https://www.opm.gov/forms/pdf_fill/sf1152.pdf