public partial class FormPrint : Form
    {
        string errorMsg;
        List<DoctorAdmission> listDoctorAdmission;
        public FormPrint()
        {
            ...
            DoctorAdmissionBindingSource.DataSource = listDoctorAdmission;

            bindingSourceDoctorAdmissionItem.DataSource = DoctorAdmissionBindingSource.Current;
            
            reportViewerAdmission.LocalReport.SubreportProcessing += new SubreportProcessingEventHandler(LocalReport_SubreportProcessing);
            
        }

        


        void LocalReport_SubreportProcessing(object sender, SubreportProcessingEventArgs e)
        {
            e.DataSources.Add(new ReportDataSource("DoctorAdmissionItem", ((DoctorAdmission)bindingSourceDoctorAdmissionItem.Current).ListAdmission));
        }
        

        private void FormPrint_Load(object sender, EventArgs e)
        {
           
           
            
            this.reportViewerAdmission.RefreshReport();
        }

void LocalReport_SubreportProcessing(object sender, SubreportProcessingEventArgs e)
        {
            List<DoctorAdmissionItemRel> listDoctorAdmissionItemRel = new List<DoctorAdmissionItemRel>();
            
            foreach(DoctorAdmission da in DoctorAdmissionBindingSource.List)
            {
                foreach (DoctorAdmissionItem dai in da.ListAdmission)
                {
                    listDoctorAdmissionItemRel.Add(new DoctorAdmissionItemRel(dai.AdmissionPacient.PersonData + " ["+dai.AdmissionPacient.PoliceNumber+"]", dai.DateTimeAdmission.ToString(), da.ID));
                }
            }
            
            
            e.DataSources.Add(new ReportDataSource("DoctorAdmissionItem", listDoctorAdmissionItemRel));
        }