the way i'm thinking it might work is this:
i'm no physicist so please help me out here if my assumptions are incorrect.
say the area of the end of the hose from the steamer is n, and the force of air coming out of that hose was x newtons or psi or however you want to measure it... aslong as the total area of all the holes on the aparatus equalled n, you'd not lose pressure, and if every hole was exactly the same area, then you'd have equal steam from all the holes. you could then work out how much pressure goes to each bottle nozzle by using x divided by the total amount of holes on the aparatus times the amount of holes on the nozzle. this is assuming perfect laminar flow, but of course that wouldn't be the case as turbulence occurs at every change in direction... but aslong as the aparatus is under pressure and all holes are the same size, the distribution would be even surely? if it weren't under pressure and you were depending on convection i'm guessing there would be problems.
Edited, sorry
and again... hehe