フォームにボタンとチャートを配置して、これを確認してください。
悪いニュースは、トレンド データで何かを変更するたびに bind 関数を呼び出さなければならないことです。
リアルタイムの更新については、chart.datasource を使用しますが、現時点ではそれをクラスと組み合わせる方法がわかりません (その方法が可能である場合)。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace chart_binding
{
public partial class Form1 : Form
{
    TrendData td = new TrendData();
    TrendData td2 = new TrendData();
    public Form1()
    {
        InitializeComponent();
        //trend data 1
        DataPoint dt1 = new DataPoint();
        dt1.DateTime = DateTime.Now;
        dt1.Value = 100;
        DataPoint dt2 = new DataPoint();
        dt2.DateTime = DateTime.Now.AddDays(+1);
        dt2.Value = 200;
        td.Add(dt1);
        td.Add(dt2);
        //trend data 2
        DataPoint dt11 = new DataPoint();
        dt11.DateTime = DateTime.Now;
        dt11.Value = 50;
        DataPoint dt22 = new DataPoint();
        dt22.DateTime = DateTime.Now.AddDays(+1);
        dt22.Value = 70;
        td2.Add(dt11);
        td2.Add(dt22);
        chart1.Series.Add("series2");
        chart1.Series[0].Points.DataBindXY(td.Select(x => x.DateTime).ToList<DateTime>(), td.Select(x => x.Value).ToList<double>());
        chart1.Series[1].Points.DataBindXY(td2.Select(x => x.DateTime).ToList<DateTime>(), td2.Select(x => x.Value).ToList<double>());
    }
    private void button1_Click(object sender, EventArgs e)
    {
        //trend data1
        DataPoint dt3 = new DataPoint();
        dt3.DateTime = DateTime.Now.AddDays(2);
        dt3.Value = 300;
        td.Add(dt3);
        //trend data2
        DataPoint dt33 = new DataPoint();
        dt33.DateTime = DateTime.Now.AddDays(2);
        dt33.Value = 150;
        td2.Add(dt33);
        //no auto-update, have to call this code every time you add something to TrendData
        chart1.Series[0].Points.DataBindXY(td.Select(x => x.DateTime).ToList<DateTime>(), td.Select(x => x.Value).ToList<double>());
        chart1.Series[1].Points.DataBindXY(td2.Select(x => x.DateTime).ToList<DateTime>(), td2.Select(x => x.Value).ToList<double>());
    }
}
class DataPoint
{
    public DateTime DateTime { get; set; }
    public double Value { get; set; }
}
class TrendData : IList<DataPoint>
{
    public List<DataPoint> myPoints = new List<DataPoint>();
    public void Add(DataPoint item)
    {
        myPoints.Add(item);
    }
    public int IndexOf(DataPoint item)
    {
        throw new NotImplementedException();
    }
    public void Insert(int index, DataPoint item)
    {
        throw new NotImplementedException();
    }
    public void RemoveAt(int index)
    {
        throw new NotImplementedException();
    }
    public DataPoint this[int index]
    {
        get
        {
            throw new NotImplementedException();
        }
        set
        {
            throw new NotImplementedException();
        }
    }
    public void Clear()
    {
        throw new NotImplementedException();
    }
    public bool Contains(DataPoint item)
    {
        throw new NotImplementedException();
    }
    public void CopyTo(DataPoint[] array, int arrayIndex)
    {
        throw new NotImplementedException();
    }
    public int Count
    {
        get { throw new NotImplementedException(); }
    }
    public bool IsReadOnly
    {
        get { throw new NotImplementedException(); }
    }
    public bool Remove(DataPoint item)
    {
        throw new NotImplementedException();
    }
    public IEnumerator<DataPoint> GetEnumerator()
    {
        return myPoints.GetEnumerator();
    }
    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
        throw new NotImplementedException();
    }
}
}