It is not about showing income. It is about showing funds for tuition fees and living. Income of parents is like a backup in case you need more money there for some unknown events/emergencies.
You should be able to show funds in the form of cash in bank, education loan, PF , FD.
If they are not in your name then you need a sponsor letter saying they r sponsoring u along with proof of funds in their name in above categories like FD.
hope its clear.
