Not really meant to be a tutorial, but just a few notes that may help others playing in the
world of Poser5 dynamic cloth.
For dynamic clothing, I do not think there are really any limits how big you can go.
One thing I do for larger sizes and also just to shape things is 'do things in parts'.
By that I mean;
1) Start with your stock figure and import your dynamic cloth.
2) Move it around so it fits reasonably close if needed.
3) Leave your figure at a stock pose during the entire process.
4) Use 30 frames and set the breast size larger at the 30th frame, but not to the final size
you might desire.
5) Run the cloth simulator for frames 1 to 30.
6) Export the 30th frame of the modified cloth as an *.obj (not as a morph object though)
7) Set key frames at the 30th frame for your figure (all parts using the animation pallet)
and break the spline on all keyframes.

Add 30 more frames to your animation
9) Delete (or hide in the hiearachy editor) the original cloth object.
10) Import the modified cloth object at frame 30 (not centered and not percent of figure, so
it will come back in just at it left.
11) Go to the 60th frame and increase the size of the breast again, or other body parts.
12) Run a new simulation for the modified cloth from frames 30 to 60.
13) Repeat the process as many times as you like.
14) Save you figure (unposed) in a library and your modified cloth object as an object.
15) Create a new file, add your figure, import your cloth object, start posing and animating
from here !
Of course the Cloth Room has many settings. You can vary what you set as constrained groups in different simulations, fold resistance, etc. All those things will affect the final shape of the cloth. Also, since you are creating in pieces, the intermidate simulations do not neccessarily have to reflect the final body shape. For example, you could do something like use the pregnant morph in one of the simulations, thereby just pushing out the front of the cloth. Something like that could make the final shape looser around the final breast size.
Generally I find doing the cloth this way works better than just doing it one animation for default to you final figure. Especially if you are trying to go very big.
Also, if you have any software to edit *.obj files, you can modify the shape along the way, further refining how you get to your final cloth object. And, if you have the software to do it, you can sub-divide the polygons. Although that can add a lot of cloth simulation time.
Sometimes I will just run the simulation up to the point where Poser quits calculating (the cloth numbers just get stuck on one frame) cancel the simulation at that point, then export, and that may be pretty close to what I want.
Attached is a really crude render of very big (well at least for me). You can see the cloth is still pretty loose. The shoulders are messed up a bit, but that could be fixed by directly editing the *.obj, or running the simulations a little different.
I started with the stock P5 summer dress on this one, then ran the simulations in 30 frame increments. Actually that is probably overkill, as this particular simulation, partly because I used 230 frames, could actually run the cloth simulation without 'breaking'.
Running this one as one simulation though, the dress looks much tighter.
Of course if you 'want' to break the cloth, then there are other things to try out.
Hope this rambling on helps get your ideas going !
StudioZ