K4 just isn't a good figure: The sculpting is uninspired, it is hard to scale and thus to age up and the rigging is quite bad, too.

I weightmapped it, but gave up shortly before I was finished because with Genesis 1 and 2 around it was simply pointless.

Sooo.....

Why not use Genesis 1 or 2 if your copy of Poser can do weightmapping ?

AND NO, YOU DO NOT NEED TO INSTALL DAZ STUDIO TO USE GENESIS IN POSER.

Simply install the (Free) DSON importer and then you can load them just like any other Poser mesh by clicking on an icon.

This one took me five minutes to make using Genesis 1:

It's 0.6 Basic Child, 1.0 thin and then scaling the shins along the y-axis to 112% and scaling up the feet a bit. The clothing "auto-converted" in 5 seconds to the new bodyshape.

Daz also sells custom morph packages for older children and teens for both Genesis 1 and 2, so whatever age you need, it's no problem for Genesis 1 or 2.