FlexReportコントロールには、FlexChartFieldというチャートを表示するための機能が備えられています。
FlexChartFieldでは複数のY軸を設定したチャートを出力することはできませんが、FlexChartコントロールを使用してチャートを作成し、これを画像に変換してFlexReportへ出力することができます。

◎サンプルコード（VB）

Imports C1.Win.FlexReport
Imports C1.Chart
Imports C1.Win.Chart

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ' レポートの読み込み
        C1FlexReport1.Load("../../FlexReportFile.flxr", "レポート 1")

        ' FlexChart画像を取得
        Dim imgFlexChart As Image = GetImageFlexChart()

        ' レポートにFlexChart画像を設定
        Dim imgField As ImageField = CType(C1FlexReport1.Fields("Field1"), ImageField)
        imgField.Picture = imgFlexChart

        ' FlexViewerに表示
        C1FlexViewer1.DocumentSource = C1FlexReport1
    End Sub

    Private Function GetImageFlexChart() As Image
        ' データの作成
        Dim dt As New DataTable()
        dt.Columns.AddRange(New DataColumn() {
            New DataColumn("X", GetType(String)),
            New DataColumn("Y1", GetType(Int32)),
            New DataColumn("Y2", GetType(Int32)),
            New DataColumn("Y3", GetType(Int32)),
            New DataColumn("Y4", GetType(Int32))
        })

        dt.Rows.Add("A", 1, 40, 300, 2000)
        dt.Rows.Add("B", 2, 10, 400, 3000)
        dt.Rows.Add("C", 3, 20, 100, 4500)
        dt.Rows.Add("D", 4, 30, 200, 3500)
        dt.Rows.Add("E", 5, 10, 500, 4000)
        dt.AcceptChanges()

        ' シリーズの作成
        Dim series1 As New Series() With {
            .Name = "series1",
            .Binding = "Y1",
            .StackingGroup = 0,
            .AxisY = New Axis() With {
                .Position = Position.Left,
                .AxisLine = True,
                .Min = 0,
                .Max = 5,
                .Title = "シリーズ1"
            }
        }

        Dim series2 As New Series() With {
            .Name = "series2",
            .Binding = "Y2",
            .ChartType = ChartType.LineSymbols,
            .StackingGroup = 1,
            .AxisY = New Axis() With {
                .Position = Position.Left,
                .AxisLine = True,
                .Min = 0,
                .Max = 50,
                .Title = "シリーズ2"
            }
        }

        Dim series3 As New Series() With {
            .Name = "series3",
            .Binding = "Y3",
            .ChartType = ChartType.Spline,
            .StackingGroup = 2,
            .AxisY = New Axis() With {
                .Position = Position.Right,
                .Min = 0,
                .Max = 500,
                .Title = "シリーズ3"
            }
        }

        Dim series4 As New Series() With {
            .Name = "series4",
            .Binding = "Y4",
            .ChartType = ChartType.Scatter,
            .StackingGroup = 3,
            .AxisY = New Axis() With {
                .Position = Position.Right,
                .Min = 0,
                .Max = 5000,
                .Title = "シリーズ4"
            }
        }

        ' 棒グラフの作成
        FlexChart1.BindingX = "X"
        FlexChart1.ChartType = ChartType.Column
        FlexChart1.DataSource = dt
        FlexChart1.Stacking = Stacking.Stacked

        FlexChart1.Series.Clear()
        FlexChart1.Series.Add(series1)
        FlexChart1.Series.Add(series2)
        FlexChart1.Series.Add(series3)
        FlexChart1.Series.Add(series4)

        FlexChart1.Legend.Position = Position.Top

        ' flexChartをpng画像としてファイルに保存
        Using fst As New System.IO.FileStream("work_ChartImage.png", System.IO.FileMode.Create)
            FlexChart1.SaveImage(fst, ImageFormat.Png, 400, 300)
        End Using

        ' pngファイルを読み込み、Excelのシートに画像として挿入
        Dim img As Image = Image.FromFile("work_ChartImage.png")

        Return img
    End Function
End Class

◎サンプルコード（C#）

using C1.Win.FlexReport;
using C1.Chart;
using C1.Win.Chart;

namespace WinC1FlexReportSampleCs
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // レポートの読み込み
            c1FlexReport1.Load("../../FlexReportFile.flxr", "レポート 1");

            // FlexChart画像を取得
            var imgFlexChart = GetImageFlexChart();

            // レポートにFlexChart画像を設定
            var imgField = (ImageField)c1FlexReport1.Fields["Field1"];
            imgField.Picture = imgFlexChart;

            // FlexViewerに表示
            c1FlexViewer1.DocumentSource = c1FlexReport1;
        }

        private Image GetImageFlexChart()
        {
            // データの作成
            var dt = new DataTable();
            dt.Columns.AddRange(new DataColumn[] {
                new DataColumn("X",typeof(String)),
                new DataColumn("Y1",typeof(Int32)),
                new DataColumn("Y2",typeof(Int32)),
                new DataColumn("Y3",typeof(Int32)),
                new DataColumn("Y4",typeof(Int32))
            });
            dt.Rows.Add("A", 1, 40, 300, 2000);
            dt.Rows.Add("B", 2, 10, 400, 3000);
            dt.Rows.Add("C", 3, 20, 100, 4500);
            dt.Rows.Add("D", 4, 30, 200, 3500);
            dt.Rows.Add("E", 5, 10, 500, 4000);
            dt.AcceptChanges();

            // シリーズの作成
            var series1 = new Series()
            {
                Name = "series1",
                Binding = "Y1",
                StackingGroup = 0,
                AxisY = new Axis()
                {
                    Position = Position.Left,
                    AxisLine = true,
                    Min = 0,
                    Max = 5,
                    Title = "シリーズ1"
                }
            };

            var series2 = new Series()
            {
                Name = "series2",
                Binding = "Y2",
                ChartType = ChartType.LineSymbols,
                StackingGroup = 1,
                AxisY = new Axis()
                {
                    Position = Position.Left,
                    AxisLine = true,
                    Min = 0,
                    Max = 50,
                    Title = "シリーズ2"
                }
            };

            var series3 = new Series()
            {
                Name = "series3",
                Binding = "Y3",
                ChartType = ChartType.Spline,
                StackingGroup = 2,
                AxisY = new Axis()
                {
                    Position = Position.Right,
                    Min = 0,
                    Max = 500,
                    Title = "シリーズ3"
                }
            };

            var series4 = new Series()
            {
                Name = "series4",
                Binding = "Y4",
                ChartType = ChartType.Scatter,
                StackingGroup = 3,
                AxisY = new Axis()
                {
                    Position = Position.Right,
                    Min = 0,
                    Max = 5000,
                    Title = "シリーズ4"
                }
            };

            // 棒グラフの作成
            flexChart1.BindingX = "X";
            flexChart1.ChartType = ChartType.Column;
            flexChart1.DataSource = dt;
            flexChart1.Stacking = Stacking.Stacked;

            flexChart1.Series.Clear();
            flexChart1.Series.Add(series1);
            flexChart1.Series.Add(series2);
            flexChart1.Series.Add(series3);
            flexChart1.Series.Add(series4);

            flexChart1.Legend.Position = Position.Top;

            // flexChartをpng画像としてファイルに保存
            using (System.IO.FileStream fst = new System.IO.FileStream(@"work_ChartImage.png", System.IO.FileMode.Create))
            {
                flexChart1.SaveImage(fst,ImageFormat.Png, 400, 300);
                fst.Close();
            }

            // pngファイルを読み込み、Excelのシートに画像として挿入
            Image img = Image.FromFile(@"work_ChartImage.png");

            return img;
        }
    }
}