So since I have spent more time in blender, I am understanding my mistakes of getting segments of models to import into FFE to give totally animated models, is the armatures I haven't focuses on.
If the object is attached to an armature. and the armature is linked to a marker of root.
It will list the bone in the mslc and that can be ffe changed.
The ffe sort order comes into play.
And you should be able to add in edited parts from blender.
Remember FFE uses the position of the object... :P
And animates off of that.
So If the position of the object is correct there should be no worries with the addition to the model.
I will have to focus on this in future.
It will be handy for adding in things like new weapons and other paraphernalia. :P Just to bling out the model.. remembering you work within the constraints of the mslc available to be replaced. :P