If two pensionable age couple are living together and they get pension.If A non dep moves in do they have to pay housing benefit?

Housing benefit is a benefit paid by the Government ( tax payers) to people who qualify because of low income to pay or help pay their rent .....if the OAPs are living in rental property they need permission from their landlord before they could 'invite' anyone and 'if' given permission the person moving in needs to pay rent to them,that changes their household income level and they have to declare that to the benefits agency (or they are committing benefit fraud) they would not continue to recieve housing benefit as the student is paying them to rent a room,

if they live in their own home then they do not get housing benefit anyway

although there is a taxable allowance available on 'rent a room'  where the OAPs would have to register for.