Editing default yfbody.blender file

Odd question...

I am creating "statues" with poses (for my use only) but want to modify the default yfbody.blender or ymbody.blender mesh (not the texture, I've noted that on the boards). Can't edit the mesh in blender (that I can tell) but wanted to replace the default. Is there any way to do that? 

I do understand the vertex/bone assignment issue. I am just wondering if anyone has attempted it.

Thanks...

Fionn