(1) If the lessee, after entering into the lease agreement, acquires a legitimate interest in making available the residential space to a third party for the latter’s use, then the lessee may demand permission to do so from the lessor. This does not apply if the person of the third party constitutes compelling cause, if the residential space would be overcrowded or if the lessor cannot reasonably be required for other reasons to permit third-party use.
(2) If the lessor reasonably can be required to permit third-party use only in return for a reasonable increase of the rent, then they may make permission dependent upon the lessee agreeing to such an increase in rent.
(3) A deviating agreement to the disadvantage of the lessee is ineffective.