Tax return credit, sharing condo need help?

I room with a friend in a condo. Rent is $1600, my parents pay the rent, my roomate pays $400.

So the condo rent agreement is under my parents name.

But my roomate has been filing for tex return credits for his $400, he is a student. However he failed to include receipts, so they're asking for the returns back

The problem is that the landlord does not allow the sublet.
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Can only the landlord issue a receipt to my roomate for the $400?

It is cost-sharing agreement between me and roommate

You don't mention for which province this is. Rent credits are provincial income tax.

You could make a copy of the rent receipt and write a note on it that $400 is the roommate's share. I don't know if this would be acceptable. I think the best idea is to call the CRA or provincial tax agency. (I live in Quebec, so I'm not sure who you would call about provincial tax questions in other provinces.)

You didn't mention how much you claimed as rent credit on your tax return. If you claimed the whole $1600, there could be a problem.

Bear in mind if anyone provides this gentleman with a receipt, then CRA will be looking at that person's tax return for the corresponding income. Is this a cost sharing arrangement or are your parents subletting?