Hi,
You need 7 Sundays, and then you can play the following schedule:
{1 2 5 8} {3 4 6 7}
{1 3 6 8} (2 4 5 7}
{1 4 7 8} {2 3 5 6}
(2 3 7 8} {1 4 5 6}
{2 4 6 8} {1 3 5 7}
{3 4 5 8} {1 2 6 7}
{5 6 7 8) {1 2 3 4}
after which all pairs of players will have been in a fourball together three times, and all triples of players will have been together in exactly one fourball.