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Apple India ID required. Buy gift cards from Amazon India
Set up an Indian Apple ID using your AU mobile number to verify.
Login into an iPhone, iPad, iPod touch, using an Indian Apple ID by going to settings > Your name > Media and purchases.
Buy Apple gift cards from Amazon India using your AU amazon account. Enter an Indian address (make sure indian address is selected) and use an international fee free card. Then load gift cards to your Apple ID.
Open up Youtube app - head to account (right bottom corner) > settings (right top corner gear icon) > purchases and memberships
Choose a plan of your liking
Set up google family before signing up to family account https://families.google/families/
Thanks OP. I was able to get it working. Only difference for me i wanted to mention was when purchasing the Apple India gift card I wasn’t prompted for an India address. Instead I added the India address in the Apple ID India account - not sure if that made a difference. I however had no issues adding the gift card balance to the Apple ID India account via the App Store which YT then used for the first monthly payment. Merry Christmas!