To answer your question, you need to carefully read your written lease with your tenant concerning the unit being rented. Its terms control the obligations you owe your tenants and they owe you unless the agreement violates state law.In all likelihood you rented your property to your current tenants without any restrictions on how many occupants of the property are on the lease. You most likely did not rent the property out per room but rented the entire property for so much per month. If true, you do not have the right to increase rent on your property if two more occupants move into the property.However, depending upon the terms of your written lease, you might be able to restrict the number of permanent occupants who stay beyond a certain number of consecutive days.