Precisely speaking, you can't copy the morphs, because that would require your clothing mesh to be identical vertex for vertex with the figure. And DAZ might have something legal to say about that. ;) What you need to do is copy the effect of the morphs. There are some programs which will attempt to do that for you, including The Tailor and Wardrobe Wizard, but you may consider their output not good enough for a marketplace item. Netherworks sells magnet sets which perform the same function, but the best (and most difficult) way is to do the morphs by hand in your modeller.