When you get Poser 4, you will be able to do conforming clothing.
Clothing is usually formed over a copy of the base figure it is for.
The clothing is more like plate armor than cloth - on its own, it does not stretch. Morphs do this.
Once conformed, the automatic morphs of the base figure called JP (joint parameters) (magnets really) will also move the conformed garment with the joint - the failure is called poke thru - skin showing through the clothing.

If the figure has been morphed into a character with a different body shape, clothing will not fit the new character - unless it has morphs to match the character morphs.

Doing clothing morphs to match a figure is a long, tedious and endless process, using a modeler, or Poser magnets.

The Tailor ( for sale at DAZ) is a program that looks at the morphs for a figure and looks at a garment made to conform to that figure, you select a figure morph, or a combination of them - figures out a plus/minus shell of where the morphed verts are and uses that to generate an automatic morph in the clothing item to match.

The clothing morph is literal - no finesse - it will almost always need touching up to look smooth - especially if the figure morphs are extreme.

You translate Wendy Woppers to a sweater, the underside of the sweater as morphed, will be a jagged nightmare.

But touching up those morphs is way easier than doing it from scratch.