No adoption papers necessary to be enrolled in DEERS or receive medical care. I married into the Army, my son from a previous relationship became a military dependent, without my husband adopting, etc.
Birth certificate (with my name only) and SS were all that was needed to add us both after marriage. Possibly, if I had listed the birth father that may have made adoption/custody issues arise in enrollment.:twocents:
But Gabriel wouldn't have the military member or the member's spouse on his birth certificate like your son did. The requirements listed below only apply to incidences of getting DEERS enrollment when you have temporary custody of a child.
If a military member or spouse is listed on the BC or adoption papers, it's a different story.
ETA
Below, I should have specified that the requirements are for what's called a "secondary dependentship" (adults dependent for various reasons and wards or foster children) which has different rules than a primary dependentship (spouses, children, children of spouses.) Secondary dependents have to provide extra paperwork to prove the Department of Defense should spend money for their benefits.