Where, in the case of a transfer of the portfolio of contracts referred to in Article L. 384-1, the transferee supplementary occupational pension fund or funds are under the exclusive or joint control of the transferor mutual insurance companies, unions or provident institutions, the assets and liabilities contributed as part of this transaction are entered in the balance sheet of the transferee fund or funds on the basis of their book value in the balance sheets of the transferor companies, mutual insurance companies, unions or provident institutions.