If Pakistan would ever steal an Indian song we would never get away with it because everyone would have first heard the Indian song, but when a Pakistani song is in a Bollywood movie Indians think its a new tune and its Indian...just like when everyone in India thought "Agar Tum Mil Jao" was original and Indian they had no idea the original was sung in the 1960s by a Pakistani singer because your industry never gave credit to the original Pakistani singer.
Pakistani singers wont go to Indian courts because India made a shady law about it...see page 1 that your fellow countryperson showed us.
As for Bollywood stealing our singers...the only one that became Indian was Adnan Sami Khan and his mother was Indian so he doesn't count. Pakistani singers are too patriotic to leave the Pakistani music industry for Indian. Sure some Pakistani singers worked for Bollywood and got paid, but they never left Pakistan they would release their songs in London work with Indian producers and release their songs both in Pakistan and India and also sell their songs to Indian movies when asked. I have no problem with that as long as the original artist is paid.
If you think Pakistani artists will ever leave the Pakistani music industry for India and become Indian you are wrong. Watch this, I'm sure you understand Urdu. Listen to the interview at 7:22 when they talk about India.