It should of been included the same way a pool, barn, cabana would be.
That said, was the recent appraisal for you? Will the seller sell it at a reduced price based on the appraisal and your ability to finance it?
You do have the right to ask that the appraiser include it in his value but not in the GLA of the house.
The cost approach does allow for it as well and so does the 1004uad form itself (amenities)