The shape of the object file is in the object file. => Blender for you.
The scale and lenght of bones is in the cr2.
Both have to match up you know.

You can do 3 things:

a) Morph Roxie into a kiddo, but maintain the lenght of all body actors. => You will have a BIG baby in Blender.
Load as a FBM in Poser, select the body actor and scale the full body down. => You WILL have to adjust the eyes joint centeres, and some other bones and magnets and probably dependencies.

b) Morph Roxie into a kiddo, and do the object file scaling in Blender, and again load as a full body moprh.
But then in Poser you have to adjust ALL bones joint centers to become in sync with the object file being scaled down.
Adjust ALL magnets, and dependencies.

c) Do as in "b", but edit the cr2 to point to you new object file, and then scale and adjust all bones. => Not for distribution!

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!