Not completely clear about what you mean, but are you asking if you airbrush 3 dummy tiers now will they match an edible layer airbrushed in a month and a half from now ie mid May? ie you are making a cake that is 4 tiers in total?
If that is so my answer would be probably not. If somebody was paying me to make a 4 tiered cake I wouldn't risk it as even a subtle difference in colour would be very obvious. You could however, fondant the dummy tiers now and then air brush all 4 cakes in mid May after you have made the edible tier.
If that is not what you mean, apologies.
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