Not sure if it was discussed here before.
Junaid Jamshed and Vital Signs became the ultimate chart-toppers in Pakistan when they composed “Dil Dil Pakistan”. This national song is still amongst the most well-known national song. Nisar Nasik is often credited for writing the lyrics of this beautiful song.
In one of his interviews with “Shamma”, New Delhi Salah-ul-Din Parvez claimed that this song was initially written by him as “Dil Dil Hindustan”. This interview was published in March, 1990 issue of “Shamma”. Salah-ul-Din Parvez said he was working on “YaadoN kay Mausam” while he wrote this song. When Salah-ul-Din Parvez visited Pakistan, he performed this song and according to him, some persons heard this song and they changed it to “Dil Dil Pakistan”. This song eventually was awarded with “Tamgha-e-Imtiaz” by the Government of Pakistan.
Sourse: Nasir Zaidi, Baad-e-Shimal (August 29, 2005)
Now the change of “Hindustan” and “Pakistan” does not disturb the balance (“Wazzan”) of the verse (“Sher”), very much. So common sense does not help much here. Dil is also a favorite topic in Urdu poetry. All I can say here is whether it was Salah-ul-Din Parvez or Nisar Nasik, Junaid Jamshed is the man who made this song famous. So Salah-ul-Din Parvez and Nisar Nasik must accept it as it is, but why:
“kion kay Dil to aik hay”
If you know some more insights pleas share them.