transposing down an octave (but leave original notes on show)

Hi all,

note sure if this is mentioned else where and i apologise if it is (please point me in the right direction).

does anyone know or is there a way that i can write say a flute line and then transpose it down an octave whilst still showing the original lines so that there could be two players playing an octave apart but playing from the same part.

some orchestral stuff we are doing is quite high so would like to have the option for the players to read the lower octave for now. 4-5 ledger lines above the stave gets confusing.

many thanks