Change Definition Of A Range Name

I have five macros that look like this

Sub Region1()
ActiveWorkbook. Names.Add Name:="Region_Name", RefersToR1C1:= _
"=Scroll.xls!Name_1"
ActiveWorkbook.Names.Add Name:="Region_Values", RefersToR1C1:= _
"=Scroll.xls!Region_1"
End Sub

Sub Region2()
ActiveWorkbook.Names.Add Name:="Region_Name", RefersToR1C1:= _
"=Scroll.xls!Name_2"
ActiveWorkbook.Names.Add Name:="Region_Values", RefersToR1C1:= _
"=Scroll.xls!Region_2"
End Sub...............

In the chart Region_Name is the name of the series Region_Values is the values of the series. I have a button for each routine. I want to use only one button instead. How?