Nathan,
The solution for the tri-ball games is known as The Fano Plane (https://en.wikipedia.org/wiki/Fano_plane), so there is no need for any programming.
Here is a schedule with the extra 4 games of regular volleyball per team:
(1 2 4) (3 6) (5 7)
(2 3 5) (4 7) (6 1)
(3 4 6) (5 1) (7 2)
(4 5 7) (6 2) (1 3)
(5 6 1) (7 3) (2 4)
(6 7 2) (1 4) (3 5)
(7 1 3) (2 5) (4 6)
Regards,
Ian