Ribbon Group to stay same size as others fall to smaller

I am using Ribbon and have several Groups in one Tab. As one reduces the width, they fall to the smaller 'Variant' size. I would like all groups to do what they are doing, except one that needs to remain still the same size. How can I acheive this? The Group contains 3 items (Button/SplitButton). I also want to have Button stay same size and the other twothat are ina Ribbon StackPanel to get one notch smaller.

I hope I am making sense. Everything works great/commands, etc. I am just in need of the resizing help.

See code below - Want the group to NEVER change size - SplitButton NEVER change size, but the two other buttons to get smaller, but show.

<apribbon:Ribbon.Tabs>
   <apribbon:Tab KeyTipAccessText="H" Label="HOME">
      <apribbon:Group ImageSourceSmall="/AMTB;component/Resources/Icons/run_16.png" Label="Task">
         <apribbon:Group.Variants>
            <apribbon:GroupVariant Priority="1" Size="Large" />
         </apribbon:Group.Variants>
         <apribbon:SplitButton Command="tbcommands:TBCommandManager.RunTask">
            <apribbon:Menu>
               <apribbon:Button Command="tbcommands:TBCommandManager.RunTask" Label="Run All" />
               <apribbon:Button Command="tbcommands:TBCommandManager.RunSelected" />
               <apribbon:Button Command="tbcommands:TBCommandManager.RunFromHere" />
               <apribbon:Button Command="tbcommands:TBCommandManager.StepThrough" />
            </apribbon:Menu>
          </apribbon:SplitButton>
          <apribbon:Separator />
          <apribbon:Button Command="tbcommands:TBCommandManager.StepThrough" />
          <apribbon:Button Command="tbcommands:TBCommandManager.StopExecution" />
      </apribbon:Group>
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and more code with Groups