Background: Given the established 2α structure of 8 Be, a realistic model of 4 interacting α clusters must be used to obtain a 8 Be+ 8 Be interaction potential. Such a four-body problem poses a challenge for the determination of the 8 Be+ 8 Be optical potential (OP) that is still unknown due to the lack of the elastic 8 Be+ 8 Be scattering data. Purpose: To probe the complex 8 Be+ 8 Be optical potential in the coupled reaction channel (CRC) study of the α transfer 12 C(α, 8 Be) reaction measured at E α = 65 MeV, and to obtain the spectroscopic information on the α+ 8 Be cluster configuration of 12 C. Method: The 3-and 4-body Continuum-Discretized Coupled Channel (CDCC) methods are used to calculate the elastic α+ 8 Be and 8 Be+ 8 Be scattering at the energy around 16 MeV/nucleon, with the breakup effect taken into account explicitly. Based on the elastic cross section predicted by the CDCC calculation, the local equivalent OP's for these systems are deduced for the CRC study of the 12 C(α, 8 Be) reaction. Results: Using the CDCC-based OPs and α spectroscopic factors given by the cluster model calculation, a good CRC description of the α transfer data for both the 8 Be+ 8 Be and 8 Be+ 8 Be * 2 + exit channels is obtained without any adjustment of the (complex) potential strength. Conclusion: The α+ 8 Be and 8 Be+ 8 Be interaction potential can be described by the 3-and 4body CDCC methods, respectively, starting from a realistic α + α interaction. The α transfer 12 C(α, 8 Be) reaction should be further investigated not only to probe of the 4α interaction but also the cluster structure of 12 C.