What is the age of the cousin?
This is an older regulation, but still the most current.
AR 680-300(3)(b) states:
b.
Dependent. Any person who bears to a sponsor any of the following relationships:
(1) The lawful spouse.
(2) An unmarried legitimate child of a sponsor (including a stepchild or legally adopted child) who is—
(a) Under 21 years of age:
(b) 21 years of age or over and not capable of self–support due to a mental or physical disability that existed prior to reaching age 21, and is dependent on the sponsor for over half of his or her support; or
(c) Under 23 years of age and enrolled in a full–time course of study in an institution of higher learning as approved by the Secretary
of Defense or Secretary of Health, Education, and Welfare, and is dependent on the member or employee for over half of his or her support.
(3) An illegitimate child whose alleged member–father has been judicially decreed to be the father of the child or judicially ordered
to contribute to the child’s support, or whose parentage has been admitted in writing by the member.
(4) A parent (including a stepparent or parent by adoption) of a sponsor or his wife, if dependent on the sponsor for over half of his
or her support.
(5) Any other person related by blood, marriage, or adoption (brother, sister, grandparent, or parent–in–law), who actually resides in the household maintained by the sponsor and is dependent on sponsor for over half of his or her support.(6) Any Army–recognized dependent who does not reside in the continental United States.