Skinning: Using a Color as StaticResource for another Color

I implemented skinning in my application. The application loads its Brushes.xaml resource dictionary which uses colors which reside in a skin-specific resource dictionary. So only one Color.xaml is loaded depending on the chosen skin.

Skin-Specific Color.xaml

    <Color x:Key="TextBoxBackgroundColor">#C4AF8D</Color>
    <Color x:Key="TextBoxForegroundColor">#6B4E2C</Color>
    <Color x:Key="ToolBarButtonForegroundColor">#6B4E2C</Color>

Brushes.xaml:

    <SolidColorBrush 
        x:Key="TextBoxBackground" 
        Color="{DynamicResource TextBoxBackgroundColor}" />
    <SolidColorBrush 
        x:Key="TextBoxForeground" 
        Color="{DynamicResource TextBoxForegroundColor}" />

As you can see, multiple colors (TextBoxForegroundColor and ToolBarButtonForegroundColor) are the same. I'd like to circumvent that as it is getting more and more confusing especially since the used colors are not recognizable by their hex value. You could advise now to merge both Colors into one but I have skins where the TextBoxForegroundColor is different from the ToolBarButtonForegroundColor.

What I would like to do is something like this:

<Color x:Key="DarkBrown">#C4AF8D</Color>

<Color x:Key="TextBoxBackgroundColor" Color={StaticResource DarkBrown} />
<Color x:Key="ToolBarButtonForegroundColor" Color={StaticResource DarkBrown} />

Is this at all possible in Xaml? I didn't find a way.