Cannot scroll to top of feature tree

Hi,

I am trying to insert a new sketch as the very first feature of an already modelled part.  If I rollback the bar to the top, the sketch within feature 1 (base-flange) remains active.  I want to change this sketch to be driven by my new sketch.  The only thing I can think of is to delete the top feature, but that means having to repair all the subsequent features.  Any ideas?

SolidworksParts And Features