I know this questions has probably been asked but I didn't see it anywhere.  If I have a feature I've created that I want to impose on a later feature how do I go about doing that?  I created a part and extruded the boss/base.  Afterwards I made a couple of cut-extrudes.  Later I did another extruded boss/base and I want to impose the previous cut extrude through the latest boss extrude.

In the image below I have the block with the holes in it and afterwards I extruded the two blocks behind it.  I would like the cut extrude feature that created the six holes in the primary block to be projected out onto the newer boss extrude feature that is the two other blocks.