When converting clothing from one figure to another, it gets a little bit more involved than just rescaling the clothing. The clothing "conforms" to the figure because the clothing skeleton is set up to bend exactly the same way as the original figure. So, if you rescale the GEOMETRY for the figure, you also have to adjust the "skeleton" of the clothing so that it bends the same as the "new" figure that the clothing will fit.

So that's why the "fit to" doesn't work initially. The joints of your figures are different. While there are clothing converters such as Wardrobe Wizard, you'd also have to find one that also provides support for the figures you're trying to fit. And I don't see them among Wardrobe Wizard's list.

Are there any other figures that have a similar body shape and size to the ones you are trying to fit?