According to the Bulletin, "[s]tarting November 30, 2015, the term 'qualified relative' will cover both same-sex and opposite-sex domestic partners of federal employees and annuitants. Children of domestic partners also will be eligible for coverage. This expanded definition only applies to the FLTCIP program, and regular FLTCIP underwriting requirements will still apply to family members seeking coverage."
Unfortunately the FLTCIP website has no information yet on this change and the OPM news page lacks information as well. We recommend checking the FLTCIP website on or near November 30. Here's a link to their eligibility page. Hopefully they will update the Declaration of Domestic Partnership form by then.