i don't know if what you're thinking is quite realistic (i don't think even at 50 you'd see that line at that angle and breast size), but i was certainly able to achieve drooping with NGM Petite.  what are your settings?  and can you find any photos of the angle and effect you want?

definition 2.0?  that might be your culprit right there.  usually, morphs aren't made to go above 1.0.  well, non-Apollo morphs, that is.

yeah, i definitely think the morph is preferable.  that's why i suggested the custom morph. personally, i don't think magnets are at all good at this kind of fine morphing in the hands of ordinary individuals (read, people who are not Capsces), so it's probably better if you have Poser 7 and the morph brush, Zbrush, or some other program you can make custom morphs in. but if you use a program external to Poser, you'd probably want to start from your present morph.  which would mean you'd have the other morphs as part and parcel of your new morph.  which might take some finagling to work with.  either you'd want a whole, new, single Full Body Morph (not a bad thing) or you'd have to make sure to reverse the settings on the chest if you set the other body parts with FBMs.  either way, you wouldn't be able to distribute it, but i don't know if that would be a problem?

but even not being a postwork maven, it's really not hard.  if i wanted the harsh line you're talking about (which again, i don't think is quite possible with the breasts you're showing), it still wouldn't be long or difficult with liquify, blur, and a quick low opacity paint with a noisy brush .   using a pen and tablet with Photoshop is much easier, but this isn't major surgery.  i've had to do a lot more extreme stuff to most of my images. especially for V4,  but even more for Aiko and others.