It boils down to this, if the morphs do not exist in the clothing then the clothing will not conform properly.  Magnets might be one solution, particularly if the mags assist conforming clothing fit the character.  But it is difficult to judge considering that you did not mention which model you are struggling to dress.  There is conforming and scale feature in the parameter/properties panel for P9 but, again, you need to have the morphs present in the clothing as in your character.  You can use Wardrobe Wizard to modify the clothing to fit, or add the morphs using Morphing Clothes.