My understanding of this mess is that Tanveer doesn't consider Imran a rich enough bakra, so holding onto him for blackmail purposes doesn't serve her purpose. So she might let the marriage happen and then break the news to Asad, (with proofs this time) who is a bigger, better bakra in Tanveer's eyes.The result being that big protective brother will go to any length for his sis's happiness.
My guess is that whatever Tanveer does or doesn't do in the Najma-Imran case will have a bearing on Asya.