(1) Adoption is admissible if it serves the best interests of the child and it is to be expected that a parent-child relationship will arise between the adoptive parent and the child. A person who has taken part for the purpose of adoption in a procurement or transportation of a child that is unlawful or that offends common decency, or who has commissioned a third party with this or rewarded them for this as a rule is to adopt a child only if this is required by the best interests of the child.
(2) A person who is not married may adopt a child only alone. A married couple may adopt a child only jointly. A spouse may adopt a child of their spouse alone. They may also adopt a child alone if the other spouse cannot adopt the child because they are incapable of contracting or have not yet attained the age of 21.