(b) Notwithstanding paragraph three of subdivision b of section six hundred of the retirement and social security law, persons in the employ of the corporation on whose behalf the corporation has made or shall make payments pursuant to paragraph (a) of this subdivision shall neither be required nor permitted to become members of the New York state and local employees' retirement system for so long as such payments continue; provided, however, that nothing in this paragraph shall be deemed to affect the rights and privileges of persons in the employ of the corporation who are enrolled members of the New York state and local employees' retirement system on the effective date of this subdivision, and further, that this paragraph shall not affect the membership of persons in the employ of the corporation who are enrolled members of the New York state and local employees' retirement system on the effective date of this subdivision.