HRA claim on sublet

I have the following query regarding sublet of property.  A is the owner of the house and has rented the house to B for Rs 10,000 per month. B has further sublet the house to C at Rs 25,000 per month. C is a salaried employee eligible to claim HRA while B is a self-employed professional who is not eligible to claim HRA. 1. While C is claiming HRA, whose PAN card needs to be furnished for the claim by C in ITR? 2. If the PAN card of owner A is furnished, then a difference in the rent paid and rent received of Rs 15,000 is shown which may invite scrutiny. 3. If the PAN card of B is furnished in ITR, then the rent received under Income from House property would not be shown to IT Department as B will show the income as 'Income from other sources', thus, may invite scrutiny. As B is not eligible to claim HRA, how will the PAN card of A gets furnished in the ITR for rent Rs 10,000 paid? 4. In this case, the income to be captured by B would be Rs 15,000? 5. What documents are required by A, B, and C to maintain the legality of the transactions of such nature.