Creates the Custody Relinquishment Prevention Involving Children with Developmental Disabilities Act. Provides that the Act establishes a pathway for families on the verge of seeking services for their child's developmental disability through relinquishment of parental custody to the Department of Children and Family Services, despite the absence of abuse or neglect, to receive services through the appropriate State child-serving agency. Requires the Department of Children and Family Services, the Department of Human Services, the Department of Healthcare and Family Services, the Illinois State Board of Education, the Department of Juvenile Justice, and the Department of Public Health to enter into an interagency agreement for the purpose of preventing children and youth with developmental disabilities who are not otherwise abused or neglected from entering the custody or guardianship of the Department of Children and Family Services solely for purposes of receiving specialized services and supports to address the child's or youth's needs. Provides that under the interagency agreement, the listed agencies shall establish an interagency clinical team to review cases of children and youth with developmental disabilities who live at home with their families and are at risk of relinquishment, and to connect the child or youth and his or her family with the appropriate services, treatment, and support to prevent custody relinquishment to the Department of Children and Family Services. Contains provisions on what issues must be addressed in the interagency agreement; annual outcomes and data reports to the General Assembly; and other matters. Requires the listed agencies to adopt rules providing that any employee of that Department who encourages a parent, guardian, or other responsible adult to relinquish custody of a child with a developmental disability solely to access specialized services and supports through the appropriate State child-serving agency, despite the absence of abuse or neglect, is subject to termination.