To establish a domestic partnership, two individuals must file a joint declaration of domestic partnership with the health department affirming that they:

    (1)    have resided together for at least six months,

    (2)    each intends to reside with the other and share the common necessities of life,

    (3)    are each 18 years of age or older,

    (4)    are mentally competent to contract,

    (5)    are not related by blood closer than would bar marriage in the State of Missouri,

    (6)    are not married to any person other than their domestic partner, and

    (7)    are each other's sole domestic partner.