This is possible. You have to tie each DropDown_change event to a common macro

Thus if your checking code  is a macro  named CheckDropDown in module1 then

Sub DropDown2_Change()
Module1.CheckDropDown
End Sub
'If there is aother drop  down to check then add

Sub DropDown3_Change()
Module1.CheckDropDown
End Sub
'''''Go on adding the drop down change events

'Now the code in CheckDropDown will be like this
'This code is added in Module1


Sub CheckDropDown()

For Each myshape In ActiveSheet.Shapes

'The following code will check for a Shape called Drop Down 2
If myshape.Name = "Drop Down 2" Then
'Do your code here
'You can even Try a case select  statement

End If

Next

End Sub