Bind Unrelated property to DataGrid - wpf

Question

EDIT: Solved
(I made another property in the ViewModel wrapper and bound to that)
I am trying to bind a property that is not related to the ObservableCollection that the DataGrid is bound to. The other columns are binding the way they should, it is just this one column that I can't seem to get to work.
I tried binding the property using RelativeSource AncestorType and directly to the DataContext with no luck.
The XAML, The ObservableCollection I am binding to obviously is called MonthlyRecords which is a collection of a different class and this is binding the way it should be. It is the property SelectedTenant.FullName which has nothing to do with the collection that is giving me grief.
<DataGrid ItemsSource="{Binding MonthlyRecords}" AutoGenerateColumns="False">
<DataGrid.Columns>
<DataGridTemplateColumn Header="Name">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<!--Trying to bind this Property in the next line-->
<TextBlock Text="{Binding Path=SelectedTenant.FullName}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTextColumn Width="60" Header="Code" Binding="{Binding UpdateSourceTrigger=LostFocus, Path=TenantCode}" />
This is the class for the property I am trying to bind.
public class Tenant
{
public Tenant()
{
}
public int Code { get; set; }
public string LastName { get; set; }
public string FirstName { get; set; }
public string FullName => LastName + " " + FirstName;
public string Section { get; set; }
public Tenant(int code, string lastName = null, string firstName = null, string section = null)
{
Code = code;
LastName = lastName;
FirstName = firstName;
Section = section;
}
}
And this is the property in the ViewModel I am trying to bind to.
private Tenant _selectedTenant;
public Tenant SelectedTenant
{
get { return _selectedTenant; }
set
{
if (Equals(_selectedTenant, value)) return;
_selectedTenant = value;
OnPropertyChanged();
}
}
What else do I need to do to get this to bind to the DataGrid?

Answer 1

<DataGridTextColumn Header="Name" Binding="{Binding Path=SelectedTenant.FullName, RelativeSource={RelativeSource AncestorType={x:Type Window}}}"/>
Edit:
I have set AutoGenerateColumns="True"
<DataGrid ItemsSource="{Binding MonthlyRecords}" AutoGenerateColumns="True">
<DataGridTextColumn Header="Name" Binding="{Binding ElementName=ComboBoxTenant, Path=DisplayMemberPath}"/>