In all such cases of Rent etc, main key to issues is always "Agreement". As said by many people above, go through rent agreement. Much has already been cited above on TDS issue so I wont talk about that.
However, being internal auditor, you must ensure that if Agreement has no mention of the people whom payment is being made on the instructions of Landlord then such instructions should be available with your client in writing to prove 1) that the payment made to these people was for Rent (in income tax) and 2) on the instructions of landlord (if tomorrow landlord dispute rent payments)
In case your client has no written instructions from landlord, advice him through audit report to get standing instructions from landlord as well as to ratify previous payments made to relatives.
Regards,
Sharad Aggarwal