Premises constituting part of the housing resources of the City of Warsaw cannot be sublet to third parties. They may only be rendered available free of charge upon prior written consent of the City. In certain legally provisioned cases, the City may refuse to issue such a consent. An apartment may be rendered available to a third party only for a fixed period of time, no longer than 3 years. These requirements have not been formally waived due to the situation in Ukraine. In your situation, it would be best to contact the local authorities in order to determine if the City Hall would be willing to waive or relax the regulations for rendering the premises available to a third party free of charge (e.g. by allowing you to apply for the required consent without providing the personal data of said Ukrainian citizens, on condition that such data is provided once the consent is granted).