750 ILCS 46/408: Additional persons to be tested.

(a) Subject to subsection (b), if a genetic-testing specimen is not available from a person who may be the parent of a child, for good cause and under circumstances the court considers to be just, the court may order the following individuals to submit specimens for genetic testing:

(1) the parents of the person;

(2) brothers and sisters of the person;

(3) other children of the person and the woman or person who gave birth to the person; and

(4) other relatives of the person necessary to complete genetic testing.

(b) Issuance of an order under this Section requires a finding that a need for genetic testing outweighs the legitimate interests of the individual sought to be tested, and in no event shall an order be issued until the individual is joined as a party and given notice as required under the Code of Civil Procedure.