Notes. Given are the current masses of the members of the binary: = 60 M_⊙ and = 2.54 + 7.4 ≃ 10 M_⊙, their relative velocity to NGC 6231: v_sys = 63 km s⁻¹, their current orbital period: P_cir = 3.41 days and orbital separation: a_{pre − CC} = 38 R_⊙. The initial mass ranges from 30 to 80 M_⊙ and ranges from 10 to 50 M_⊙. Only solutions with a high γ_RLOF and a low β_RLOF, so when a lot of angular momentum leaves the system due to nonconservative mass transfer, seem to give a a_ZAMS that could be large enough to avoid merging of the system. For comparison: HD 153919 with a mass of 60 M_⊙ has a radius of 25 R_⊙.