aRtBee, I was originally going to use the conforming version and just clothify the hip part as I usually do but I've used many corrective morphs for the upper arms and collars that the straps just woudn't behave so I figured "why not make the whole thing dynamic?".   At some point I did try your suggestion but the skirt part separated from the rest of the dress. 

EnglishBob, thank you, unfortunately I only have the free version but will try saving the .obj through that as I recall that fixes some things.

In any case, I just ended up using the dress as a conforming item and it didn't turn out that bad :)