5 C.F.R. § 894.509
What are the QLEs that are consistent with increasing my type of enrollment?
(a) Marriage; except for a TEI who is an unremarried survivor, widow or widower; TEI former spouse; and TEI child(ren);
(b) Acquiring an eligible child or TEI child; or
(c) Loss of other dental or vision coverage by an eligible family member or TEI family member.