Bruce,
No problem
To not close any doors my advice is preference RAAF Pilot at DFR and then when you get the Flight Screening paperwork aircrew service preference form, preference all three as "Most Preferred" on the 3 box form or "5 out of 5" for the 5 box form.
Preferencing more than one job at DFR will make it harder for you to get through Assessment Day considering you can just change your preferences at FSP.
For example on my Flight Screening guys only preferenced RAAF pilot at DFR and ended up getting offers for Army and Navy afterwards anyway as well as RAAF offers.
Good luck,
fs