3levels+ blendshape export problem [FBX][Blendshape]


Hi, I’ve some serious problem that i’m trying to solve it.

   First I've a model with 3 level Blendshape so what is 3 level mean?. Imagine that I've a shapes i want to blend so i blend it to first base model (head or body or anything ). Then i blend the second model(that base model) to the third model which will be the final model that i gonna use as my result. Why? because there will be added a lot of function between second and third base model it's a requirement in our pipeline.
   So the problem is with the third model (The final model) that i wanted it to be export. After exported it as the FBX file (The third model and the skeleton included) Only blendshape node in third model survived which "it'll be blending following the second model only" <-- here is the problem because the second model doesn't have any blendshape node left, the FBX Export get rid all of it. Without blendshape in the second model so i lost all the facial movement data in from the shape models the blended to the second model.

Example preventing for misunderstanding*
To be clearly.
-You guy could be try to create the Polygon A,B,C,D then
-Select A and B and blend it to C
-Select C and Blend it to D
-Exported D As FBX

There will be the same problem i had.

Any solution are welcome