This described accurately the process I have been partly involved in with a customer lately.
US: Please review our acceptance plan in the attached SOW and let us know if you would like to modify it.
Customer: You must use our plan.
Us: Please send us a copy of your acceptance plan.
Customer: We cannot let you see the plan without a signed NDA.
Us: We have a signed NDA with Customer!
Customer: Okay, I will send you our plan.
Us: Thank you.
Customer: We cannot send you our plan because we do not have one! Can we use yours?
Us: Falls out of chair.