provisions of section forty and such remodeled or reconstructed apartments shall be available for occupancy by eligible elderly persons of low income only to the extent that no eligible veterans apply for such units; provided, that if no eligible veterans or elderly persons of low income apply for such remodeled or reconstructed units, the units shall be made available to other persons of low income living in substandard housing. Notwithstanding the requirement that each project shall be based upon a separate application made to the department, the department may consolidate two or more projects of the same housing authority, for which projects applications have been seasonably made under this section and which projects shall have been approved by the department, into a single project, and may make on behalf of the commonwealth a contract with the housing authority for state financial assistance in respect of such consolidated project superseding any such contract made in respect of any of the constituent projects, and may determine the date of completion of the consolidated project superseding any such date determined in respect of any of the constituent projects and such consolidated project shall be constructed, financed and managed as a single project; provided, that nothing contained in this sentence shall affect the rights of the holders of any notes outstanding in respect of any of the constituent projects at the time of such consolidation.