I have to admit, I adore the sight of a pair of enormous, well-stuffed bra cups!
Having said that, 'pair' of cups is almost pushing that definition to its limits at this point! As a bra needs to support more breast, invariably the cups need to become larger, and larger, and larger. Often cups are seperated in more modest sizes, but eventually, this becomes inefficient as we continue to scale up the design. The 'gore' or 'bridge', the piece of structural material that sits between the two cups and rests on the sturnum, is great for extra support, and seperating the cups is better for comfort and breathabbility, but takes up valuable real-estate. As breasts get bigger, every square millimeter of space on the chest counts, and keeping the bridge and/or underwires close to the body only serve to seperate the breasts and push them further apart - often less preferable when trying to minimise the obvious signs of being well-endowed.
In fact, underwires* only tend to have limited usability also. Firstly for the reason above, but secondly because there is only so much width and depth to the torso that the underwire can actually sit on. Beyond a size where it can actually fit onto the rib-cage for support, it then becomes a hindrance more than a help. Underwires would also make it harder to put a bra on, eventually having to be carefully slotted into place at the base of the breast - and 'careful' isn't so much of an option when you're struggling with two soft, heavy, wayward flesh balloons!
And so, the 'gore' or 'bridge' actually becomes more of a 'joining piece' between the cups, removing the seperation between the breasts and utilising as much space as possible in front of the chest. It has it's downsides - skin against skin, especially in the case of such a generous cleavage will cause a woman to glow a little more in that area, as it is less breathable generally speaking. However, at any serious size, it is always going to be a compromise. The main objective is that the bra does something to support the well-endowed wearer. As a result of this, the definition between the two individual 'cups' can become less and less obvious in the search for volume and size. This example has some extra reinforcement and adjustment built in to provide, perhaps negligable, control and support.
The cups themselves are a compromise of a scaled-up design; built purely for sheer capacity they no longer point forward, but rather clumsily face outward at a 45 degree angle. The side panel (between the cup and the band) is also utilised for further capacity, especially when the garment over-filled a little. The straps themselves are a relic brought forward, struggling to spread the load of such heavy breasts and only just within specification, but perhaps the best a custom bra store could manage at short notice?
Custom Cups aren't strangers to well endowed damsels, of course, althought our protagonist here is perhaps on the rarer and larger side of their clientele. The real issue, it would seem, is that the poor girl seems to have grown significantly larger in just the week that she has been measured. To put her recent development into context, many women won't reach 6 cup-sizes in their entire life! (That's an E-cup in the UK, or a DDD-cup in the US!)
Whilst most bras can take at least a little over-loading, the effects of a bra potentially busting at this size could be quite dramatic, both physically and financially! Whilst it seems like it is taking the strain for the moment, would it be able to handle another six cup-sizes by next week? Hmm...
*Bonus fact: Did you know that underwires actually come in different shapes and profiles, to better suit certain breast shapes? If you thought bra-sizing could be confusing and inconsistent, bear in mind it isn't always 'one cup-size fits all' even if your size is right!