This is unrelated to NURBS but just a heads up for FBX in general.
I saw a Developer Update for Godot where Gordon McPherson said he did a lot of work on the FBX import and export compatibilities in Godot which indirectly Blender’s exporter was also going to benefit a lot from (he mentioned that it could eliminate problems with Maya exchanges).
Don’t know how much of this is already done or went into Blender already but he mentioned that he is glad for anyone helping or asking him about this because it was just so much work and he wants anyone to benefit from it. 
Just posting this here, for the chance that it maybe is something that could impact your work.
If not - just ignore this post. 