The Case of Easy Manipulation
Let us perform the reverse Engineering of the vote on the General Assembly seats. There are 272 Parliamentarian seats in the National Assembly; whereas, there are only 20-25 seats that have a true bulk of a large populace dwelling outside Pakistan. So, if there are Nine Million overseas Pakistanis then half of them are having valid votes hypothetically (Passport and NICOP requirements) to take into consideration.
Also, we might overestimate the effect of overseas voting. There are around 9 million overseas Pakistanis total, how many will vote, even to assume 50% voter turnout is a lot if you look at our past elections and elections around the world. Although I think that only, 10 lac people would vote out of 90 lac. But the split per constituency by average votes is 9 Million/25 seats. Given the overseas turn out to be roughly fifty, it would mean roughly 62,500 more votes that can be bagged. And then if by per-centile if they are split into the third quartile for the first three candidates, there is a fair 15000 additional votes for the runner-up candidate.