They have migrated since 1950s and most first generation are probably grandparents now with their own families in UK why are they still sending remittance of Pakistan ?
The process of migration is still ongoing. There are 10x more overseas Pakistanis migrated from 2000s than what you are assuming from 1950s or even 1960s migration of Mangla Dam. This topic is irrelevant as the inflow of remittance is increasing each year with double digits and the total amount already explains what I am trying to say.
Remittances usually come for only one generation, not beyond that.
That is why Pakistan received only 18 billion dollars of remittances last year. There are almost as many Pakistanis in UK as in Saudi Arabia but the remittances received from labour class of Saudi Arabia was more than UK due to the very reason you have highlighted above.
Remittances are not added to GDP.
My friend I don't know why you sometimes over-read my post. I request you to please read the meaning of what I say and do not speculate.
Who said that remittance is added in GDP?
All I am saying is gdp per capita is better in those areas where concentration of overseas Pakistanis is more. Overseas Pakistanis sends remittance to their kith and kin and they reinvest in Pakistan . For example the area I live in Gujrat, I heard 30 years ago most of the people were poor except few families and now I don't remember a single house in my neighbourhood of 50 families whose son or daughter is not abroad. Most of them are in UK, Italy and Saudi Arabia and for example my neighbours next door were quite poor and I heard they even used to accept "zakat" and now after the fortunes changed they own like 10 shops, 5 houses and several franchises in my city, all thanks to foreign funded money sent by their family members from UK and Japan.
It is true for most of the overseas Pakistani families, If you visit Mirpur you will see massive mansionette, bungalow and large houses owned by overseas Pakistanis and many of them claims to own different businesses in Pakistan. Even the richest Pakistani Sir Anwar Parvez is residing in UK since 1960s but he owns several businesses in Pakistan including cement and banking sector.
Such thing do factor in GDP per capita as the actual money is invested and net profits earned inside Pakistan.