I'm a bit new to excel VBA and wondered if it is possible to pass a UDF
reference as an argument to a UDF as in:

Sub S1( subReference )
subRefrence()
End Sub

Sub S2()
End Sub

Call S1(S2)

If it can not be done cleanly, is there a workaround such as passing
the name of the function as an argument and then somehow evaluating it
inside the UDF?

Thanks for any clues.