Over on the Daz Forums, Richard Hasseltine sorted this out: the morphs have to be saved as morph assets (and reapplied or at least reloaded) to impact clothes.
When making Veronique Thibeaux, I used two merchant resources, RareStone's G8F face package and Handspun Studio's G8F body morph kit. I dialed in the basics, zeroed out all the Daz morphs (from G8F base—I don't have the Daz face or body morph sets) and the mouth realism and navel morphs, then exported the figure as a level 0 .obj. I modified it in Modo (actually, I did that for the face and the body separately, but…), then brought those in as morphs that I applied to a blank G8F. All good. Veronique looks great. However, unless I use dForce, the clothes aren't fitting on her properly. I think this was a problem with Madeline so I reverted back to the Daz breast morphs. However, I don't like them as much as I like the look I got via Handspun Studio's morphs plus my own modeling work. And I may eventually want to sell custom figures (which is why I bought merchant resources).
Is there any way I can work around this and get clothes to fit kinda okay? If I sell a figure on Rendo, for example, will everybody who buys it have crappy fits unless I deliver Daz-Standard breasts?