Do you mean:
The PAF is now proposing to China to purchase all of the PLAAF's currently operational J-10C fighter jets. When the PLAAF commissions its new J-16/J-20/J-35 fighter jets and retires the J-10C, these J-10C aircraft will be directly delivered to the PAF?
Really?
The PLAAF currently has a very large number of J-10C aircraft, and the PAF is unable to acquire all of them. If the PAF were to acquire a portion of the J-10C aircraft, China would likely be happy to agree.
The problem lies in negotiating the quantity, price, and payment methods.
However, I believe the PAF will not make such a request. Pakistan does not like second-hand Chinese weapons.