Is it permissible to pay two years' rent in advance to a relative in exchange for receiving an additional 10,000 EGP per month on top of what he pays the landlord, knowing that he does not possess the amount?

Every loan that stipulates an increase is forbidden by the consensus of scholars. Taking an increase on it is usury (riba). Therefore, it is not permissible to lend your relative a sum of money on condition that he returns it to you with an increase.