What is it called when a tenant substitutes another tenant's place in the lease but does not fully relieve themselves from liability?

The situation described, where a tenant substitutes another tenant in the lease but retains some degree of liability, is known as subletting. In this arrangement, the original tenant (sub-lessor) brings in a new tenant (sub-lessee) to occupy the premises and pay rent, while still remaining responsible to the landlord under the original lease agreement. This means that if the sub-lessee fails to pay rent or causes damage, the original tenant can still be held accountable.

In contrast, a lease assignment involves the original tenant transferring their entire interest in the lease to another party, thereby completely relieving themselves of liability. This distinguishes the two concepts, as subletting allows for a partial retention of responsibility by the original tenant. The other options listed do not pertain to this specific scenario regarding liability in tenancy agreements.