Loading user controls dynamically in Mainwindow when value in dropdown changes

'm working on a C# WPF application.I've a list of user controls UC1,UC2 and UC3.And all internally refer to another common user control called UCB. And my App.xaml refers to MainWindow.xml

UCB has a dropdown list with names of different account types.

I need to programmatically show the user control in MainWindow depending upon the account type selected in the Base user control UCB.How do I achieve this please?

My thoughts so far: May be I can instantiate all my user controls in MainWindow.xaml.cs file like this:

    UserControl uc1 = (UserControl)assembly.CreateInstance(string.Format("{0}.MyUC1", type.Namespace));
    UserControl uc2 = (UserControl)assembly.CreateInstance(string.Format("{0}.MyUC2", type.Namespace));   

userControls.Add("1", uc1);
userControls.Add("2", uc2);
and then use the MainWindow.xaml's content property to set the desired user control based on the dropdown value.

this.Content = userControls["1"];
But how do I access this content property inside ComboBox_SelectionChanged event in UCB control??

Please advise.

Thanks.