The administrator may grant an appropriate adjustment of a maximum rent where he finds that there has been, since March 1, 1959, a subletting without written consent from the landlord or an increase in the number of adult occupants who are not members of the immediate family of the tenant, and the landlord has not been compensated therefor by adjustment of the maximum rent by lease, or by order of the administrator, or pursuant to the State Rent Act or the Federal Act. Such adjustment shall be effective only during the period of subletting or increase in the number of tenants.