C# 如何在silverlight 4文本框中合并标签合并字段？

我想在silverlight 4中实现这一点，实际上我正在silverlight 4 richtextbox中实现邮件合并模块。我想在邮件合并字段单击邮件合并选项卡时插入标签字段。我怎样才能做到这一点。我需要做什么

我加了名、姓和职务。现在我想做的是，只要在邮件合并选项卡中单击名字，就在richtextbox中插入名字

public List<Employee> Employees
    {
        get
        {
            return employees;
        }
    }
private List<Employee> employees = new List<Employee>()
                {
                    new Employee()
                    {
                        FirstName = "Andrew",
                        LastName = "Fuller", 
                        JobTitle = "Director - Finance",
                    }, 
                    new Employee()
                    {
                        FirstName = "Nancy",
                        LastName = "Davolio", 
                        JobTitle = "Director - Human Resources",
                    },
                    new Employee()
                    {
                        FirstName = "Robert",
                        LastName = "King", 
                        JobTitle = "Engineering Design Manager",
                    },
                    new Employee()
                    {
                        FirstName = "Margaret",
                        LastName = "Peacock", 
                        JobTitle = "Finance & Investments Officer",
                    }
                };