There are no good solutions to this problem as it is not possible to balance the opponents. The following schedules should be about the best possible, where some pairs never oppose and other pairs oppose twice.
[(M4 F4)v(M1 F2)] [(M2 F1)v(M3 F3)]
[(M1 F4)v(M2 F3)] [(M4 F2)v(M3 F1)]
[(M4 F1)v(M2 F4)] [(M3 F2)v(M1 F3)]
[(M4 F3)v(M2 F2)] [(M3 F4)v(M1 F1)]
[(M4 F6)v(M6 F4)] [(M2 F2)v(M5 F3)] [(M3 F1)v(M1 F5)]
[(M2 F1)v(M4 F4)] [(M5 F5)v(M1 F3)] [(M6 F6)v(M3 F2)]
[(M2 F5)v(M4 F2)] [(M1 F4)v(M6 F3)] [(M3 F6)v(M5 F1)]
[(M4 F3)v(M5 F6)] [(M6 F2)v(M1 F1)] [(M2 F4)v(M3 F5)]
[(M2 F6)v(M1 F2)] [(M5 F4)v(M6 F5)] [(M4 F1)v(M3 F3)]
[(M2 F3)v(M6 F1)] [(M4 F5)v(M1 F6)] [(M5 F2)v(M3 F4)]
In the area of mixed doubles the only balanced schedules are ones where the players are spouse pairs who never meet.
See this post for more details.