C#

namespace WindowControlTest
{
    public partial class WindowMain : Form
    {
        public WindowMain()
        {
            InitializeComponent();

            int iPlayers = 4;
            UserControl uctlPlayerPane = new UserControl();

            switch (iPlayers)
            {
                case 2:
                    uctlPlayerPane = new uctl_2Player();
                    break;

                case 3:
                    uctlPlayerPane = new uctl_3Player();
                    break;

                case 4:
                    uctlPlayerPane = new uctl_2Team();
                    break;

                case 6:
                    uctlPlayerPane = new uctl_2Player();
                    break;

            }
            uctlPlayerPane.Location = new Point(25, 25);
            this.Controls.Add(uctlPlayerPane);
        }
    }
}

public interface ICalculatable
{
    DateTime FirstPaymentDate { get; }
    decimal MonthlyCompoundingRate { get; }
}

public interface IBaseObject : ICalculatable
{
    string Identifier { get; }
   // Input Value
    DateTime FirstPaymentDate { get; set; }
   // Input Value
    decimal InterestRate { get; set; }
}

public class BaseObject : IBaseObject
{
    ...
}