In the following schedule, teams 1 & 8 as well as any pair of teams whose difference is 3 can share the same stadium (complementary pairings).
7 or 8 teams
Rd Pairings
1: 1-8 5-4 7-2 6-3
2: 8-5 2-1 4-6 3-7
3: 2-8 6-5 1-3 7-4
4: 8-6 3-2 5-7 4-1
5: 3-8 7-6 2-4 1-5
6: 8-7 4-3 6-1 5-2
7: 4-8 1-7 3-5 2-6
The first named team in each pairing is the home team. Check a similar discussion from about six months ago:
Help on constrained round robin***Edited changes follow***
You mentioned different districts--are there any games between districts? Is it a 16 team round robin plus an additional game(s) intradistrict? Assuming no interdistrictal play before playoffs and two separate eight team round robins, two of your three teams could have complementary pairing numbers while the third team has a complementary pairing number of the one team in a separate district.