UV packing in Painter, can we control the scale?

Hi there,

We are importing a fbx model into painter, where each individual part is already unwrapped, but some of the UV islands are overlapping. The following import options gives good results:

However, are UVs are normalized with a constant texel density, and we don't want to loose track of their scaling, in order to get the materials tiling values right later on.
If any scaling happens during the UV packing process, is it uniform accross the different UV islands?
Is there an option to prevent any scaling on the UVs during the packing process?
Alternatively, can we query the total UV area for a given texture set, using the python API? That way, we could figure out the scaling that was introduced by the packing process, where scaling= sqrt(new-uv-area / old-uv-area) 

Thank you!

Isabelle