Well, from my experience, when I get really large swelling (which happens only when I add pressure with my breath) then they are wide apart directly after taking off the domes, but they come closer together, there's no gap at all when they become soft again. But if I get weak swelling, they stay wide apart which is really annoying. For that reason I don't really know if they are getting wider or not, if they are growing in the centre too, sometimes I have a gap between breasts, sometimes not, just depending on how big the swelling was .
But since they do touch couple of hours later when I get larger swelling, I somehow think even if not the whole area of the breasts is inside of the domes,it is affected, couple of hours later they do widen, the part in the centre that was flat gets filled (and before brava, I always had a gap between breasts, they are widely spaced), but as I already said with smaller swelling it remains flat for ever.
But since they do touch couple of hours later when I get larger swelling, I somehow think even if not the whole area of the breasts is inside of the domes,it is affected, couple of hours later they do widen, the part in the centre that was flat gets filled (and before brava, I always had a gap between breasts, they are widely spaced), but as I already said with smaller swelling it remains flat for ever.