Previously I applied visitor visa for my kids but today I got email that I need to do additional payement and also apply for study permit for kids. I can see in my GCKey the payement reciept upload section but cannot upload or change new study permit application pack for my kids.
Do I need to upload here or make changes in my profile?
Complete the study permit application forms for them and pay the outstanding fees. Combine all documents into 1 pdf (including the PoP) and upload to the receipt placeholder.
You should have posted this in the "International Students" forum, you'd get more traction there.