public class SampleProjectData
    {
        public static ObservableCollection<Product> GetSampleData()
        {
            DateTime dtS = DateTime.Now;


            ObservableCollection<Product> teams = new ObservableCollection<Product>();
            teams.Add(new Product() { PDName = "Product1", OverallStartTime = dtS, OverallEndTime = dtS + TimeSpan.FromDays(3),  });


            Project emp = new Project() { PName = "Project1", OverallStartTime = dtS + TimeSpan.FromDays(1), OverallEndTime = dtS + TimeSpan.FromDays(6)  };
            emp.Tasks.Add(new Task() { StartTime = dtS, EndTime = dtS + TimeSpan.FromDays(2), TaskName = "John's Task 3" });
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(3), EndTime = dtS + TimeSpan.FromDays(4), TaskName = "John's Task 2" });
            teams[0].Projects.Add(emp);


            emp = new Project() { PName = "Project2", OverallStartTime = dtS + TimeSpan.FromDays(1.5), OverallEndTime = dtS + TimeSpan.FromDays(5.5) };
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(1), EndTime = dtS + TimeSpan.FromDays(4), TaskName = "Victor's Task" });
            teams[0].Projects.Add(emp);

            emp = new Project() { PName = "Project3", OverallStartTime = dtS + TimeSpan.FromDays(2), OverallEndTime = dtS + TimeSpan.FromDays(5) };
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(1), EndTime = dtS + TimeSpan.FromDays(4), TaskName = "Jason's Task 1" });
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(7), EndTime = dtS + TimeSpan.FromDays(9), TaskName = "Jason's Task 2" });
            teams[0].Projects.Add(emp);

            teams.Add(new Product() { PDName = "Product2", OverallStartTime = dtS, OverallEndTime = dtS + TimeSpan.FromDays(3) });

            emp = new Project() { PName = "Project4", OverallStartTime = dtS + TimeSpan.FromDays(0.5), OverallEndTime = dtS + TimeSpan.FromDays(3.5) };
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(1.5), EndTime = dtS + TimeSpan.FromDays(4), TaskName = "Vicky's Task" });
            teams[1].Projects.Add(emp);

            emp = new Project() { PName = "Project5", OverallStartTime = dtS + TimeSpan.FromDays(2), OverallEndTime = dtS + TimeSpan.FromDays(6) };
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(2.2), EndTime = dtS + TimeSpan.FromDays(3.8), TaskName = "Oleg's Task 1" });
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(5), EndTime = dtS + TimeSpan.FromDays(6), TaskName = "Oleg's Task 2" });
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(8), EndTime = dtS + TimeSpan.FromDays(9.6), TaskName = "Oleg's Task 3" });
            teams[1].Projects.Add(emp);

            emp = new Project() { PName = "Project6", OverallStartTime = dtS + TimeSpan.FromDays(2.5), OverallEndTime = dtS + TimeSpan.FromDays(4.5) };
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(0.8), EndTime = dtS + TimeSpan.FromDays(2), TaskName = "Kim's Task" });
            teams[1].Projects.Add(emp);


            teams.Add(new Product() { PDName = "Product3", OverallStartTime = dtS, OverallEndTime = dtS + TimeSpan.FromDays(3) });

            emp = new Project() { PName = "Project7", OverallStartTime = dtS + TimeSpan.FromDays(5), OverallEndTime = dtS + TimeSpan.FromDays(7.5) };
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(1.5), EndTime = dtS + TimeSpan.FromDays(4), TaskName = "Balaji's Task 1" });
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(5), EndTime = dtS + TimeSpan.FromDays(8), TaskName = "Balaji's Task 2" });
            teams[2].Projects.Add(emp);

            emp = new Project() { PName = "Project8", OverallStartTime = dtS + TimeSpan.FromDays(3), OverallEndTime = dtS + TimeSpan.FromDays(6.3) };
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(1.75), EndTime = dtS + TimeSpan.FromDays(2.25), TaskName = "Li's Task" });
            teams[2].Projects.Add(emp);

            emp = new Project() { PName = "Project9", OverallStartTime = dtS + TimeSpan.FromDays(2), OverallEndTime = dtS + TimeSpan.FromDays(6) };
            emp.Tasks.Add(new Task() { StartTime = dtS + TimeSpan.FromDays(2), EndTime = dtS + TimeSpan.FromDays(3), TaskName = "Stacy's Task" });
            teams[2].Projects.Add(emp);

            return teams;
        }
    }

above is an sample data where i am grouping them with static data in the same way i need to for teh data which is cmg from DB and i need to store them list

all these three data are comig from different services. and i am storing them in a list now i have three tables data
Product , Project, Task.
all the data are coming from webservies. i have created three list where i am storing the data in list.

Listobjpro= new List(); Listobjproduct= new List(); LIstobjTask= new List();

now what i need to do is i need to do the mapping between these tables. if you see above. i have object of Product under Product i have added object of Project and then under project object i have added task object. now from the above data which is stored in the list i need to do the same mapping between class.

and group the data.

public class Product : INotifyPropertyChanged
    {
        public Product()
        {
            this.Projects = new ObservableCollection<Project>();
        }
        public string PDName { get; set; }
        public ObservableCollection<Project> Projects { get; set; }
        private DateTime _st;
        public DateTime OverallStartTime
        {
            get { return _st; }
            set
            {
                if (this._st != value)
                {
                    TimeSpan dur = this._et - this._st;
                    this._st = value;
                    this.OnPropertyChanged("OverallStartTime");
                    this.OverallEndTime = value + dur;
                }
            }
        }
        private DateTime _et;
        public DateTime OverallEndTime
        {
            get { return _et; }
            set
            {
                if (this._et != value)
                {
                    this._et = value;
                    this.OnPropertyChanged("OverallEndTime");
                }
            }
        }

        #region INotifyPropertyChanged Members

        protected void OnPropertyChanged(string name)
        {
            if (this.PropertyChanged != null)
                this.PropertyChanged(this, new PropertyChangedEventArgs(name));
        }
        public event PropertyChangedEventHandler PropertyChanged;

        #endregion
    }
    public class Project : INotifyPropertyChanged
    {
        public Project() { this.Tasks = new ObservableCollection<Task>(); }
        public string PName { get; set; }
        public ObservableCollection<Task> Tasks { get; set; }
        DateTime _st;
        public DateTime OverallStartTime
        {
            get { return _st; }
            set
            {
                if (this._st != value)
                {
                    TimeSpan dur = this._et - this._st;
                    this._st = value;
                    this.OnPropertyChanged("OverallStartTime");
                    this.OverallEndTime = value + dur;
                }
            }
        }
        DateTime _et;
        public DateTime OverallEndTime
        {
            get { return _et; }
            set
            {
                if (this._et != value)
                {
                    this._et = value;
                    this.OnPropertyChanged("OverallEndTime");
                }
            }
        }

        #region INotifyPropertyChanged Members

        protected void OnPropertyChanged(string name)
        {
            if (this.PropertyChanged != null)
                this.PropertyChanged(this, new PropertyChangedEventArgs(name));
        }

        public event PropertyChangedEventHandler PropertyChanged;

        #endregion
    }
    public class Task : INotifyPropertyChanged
    {
        public string TaskName { get; set; }
        DateTime _st;
        public DateTime StartTime
        {
            get { return _st; }
            set
            {
                if (this._st != value)
                {
                    TimeSpan dur = this._et - this._st;
                    this._st = value;
                    this.OnPropertyChanged("StartTime");
                    this.EndTime = value + dur;
                }
            }
        }
        private DateTime _et;
        public DateTime EndTime
        {
            get { return _et; }
            set
            {
                if (this._et != value)
                {
                    this._et = value;
                    this.OnPropertyChanged("EndTime");
                }
            }
        }

        #region INotifyPropertyChanged Members

        protected void OnPropertyChanged(string name)
        {
            if (this.PropertyChanged != null)
                this.PropertyChanged(this, new PropertyChangedEventArgs(name));
        }

        public event PropertyChangedEventHandler PropertyChanged;

        #endregion
    }