Complete fusion excitation functions for ^11,10B+¹⁵⁹Tb and ^6,7Li+¹⁵⁹Tb have been reported at energies around the respective Coulomb barriers. The measurements show significant suppression of complete fusion cross-sections at energies above the barrier for ¹⁰B+¹⁵⁹Tb and ^6,7Li+¹⁵⁹Tb reactions, when compared to those for ¹¹B+¹⁵⁹Tb. The comparison shows that the extent of suppression of complete fusion cross-sections is correlated with the 𝛼-separation energies of the projectiles. Also, the measured incomplete fusion cross-sections show that the 𝛼-particle emanating channel is the favoured incomplete fusion process. Inclusive measurement of the 𝛼-particles produced in ⁶Li+¹⁵⁹Tb reaction has been carried out. Preliminary CDCC calculations carried out to estimate the 𝛼- yield following ⁶Li breaking up into $\alpha + d$ fail to explain the measured 𝛼-yield. Transfer processes seem to be important contributors.