Accessing multiple view models - wpf

Question

I have 2 simple user controls and 2 view models that bind to them. I now want to add these to a master user control but want to know the correct way of accessing ViewModel properties from View 1 in my View 2 in the text block named FromView1?
My View 1:
<UserControl x:Class="v1"
.....
<Grid>
<TextBlock Text="{Binding Text1}" />
</Grid>
</UserControl>
My View 2:
<UserControl x:Class="v2"
..
<Grid>
<StackPanel>
<TextBlock Text="{Binding Text2}" />
<TextBlock x:name="FromView1" Text="{Binding Text1}" Background="Red" Width="100" />
</StackPanel>
</Grid>
</UserControl>
My main view containing View 1 and View 2
<UserControl x:Class="vMain"
....
<Grid Margin="20">
<StackPanel>
<local:v1 x:Name="v1"/>
<local:v2 x:Name="v2"/>
</StackPanel>
</Grid>
</UserControl>

Answer 1

Instead of having two separate view models, you should merge them into one single MainViewModel. v1 and v2 would should then share the DataContext with the vMain view which means they can bind to whatever property they want do.
So simply set the DataContext of vMain to an instance of MainViewModel and make sure that you don't set the DataContext of v1 or v2 explicitly somewhere.
UserControls should generally speaking not have their own view models. They should inherit the DataContext from their parent, which is usually a window.
If your view models tend to get big, you could use partial classes to split the definitions across several source code files.

Answer 2

your mainView's Viewmodel need to have ViewModel1 and ViewModel2
public class MainViewModel
{
....
public ViewModel1 vm1 {get;set;}
pulbic ViewModel2 vm2 {get;set;}
....
}
Xaml is ..
<UserControl x:Class="vMain"
....
<Grid Margin="20">
<StackPanel>
<local:v1 x:Name="v1" DataContext="{Binding vm1}"/>
<local:v2 x:Name="v2" DataContext="{Binding vm2}"/>
</StackPanel>
</Grid>
</UserControl>