With enough dial spinning, you probably could duplicate it. And the two shapes are similar in shape and size already. But, there is almost nothing in the way of content for Genesis child. (Unless of course anything Genesis can wear, the child can wear too. I haven’t tried that a whole not so I don’t know for 100% certainty. I can make some test runs if you like!)
Toddler might have more content and perhaps more skin textures.
My first initial feelings is stick with Genesis Child. But perhaps someone more knowledgable can jump in and give a second opinion.
Clothing for genesis will work on the genesis child shape…there are many items that are suitable for children. Smay’s bad guy includes jeans and shirt which does well on a child and there are many others that are also suitable.
I own the toddler as I bought it pre genesis…IMHO it would not be worth buying for use with genesis. It is easier to spin dials than to use gen x to convert it to genesis. If you are planning on using it with k4, then yes it is worth it.