[jbfan]

The same 3-way switch cannot have the power feed AND the feed to the load.

Sure it can!

i want to add sconce above top switch to be controlled by 3-way i can grab neutral wire from another source near by where do i hook up new light hot wire to on three way switch?

You just can not steal a neutral from somewhere.
You need a wire from the exsisting fixture to the sconce location to make this work.