C:
Let's call the teams A1, A2, ..., A7, and B1, B2, ..., B7.
Try this:
1) A1, A6; A2, A5; A3, A4; A7, B7; same pairs of Bs as pairs of As
2) A2, A7; A3, A6; A4, A5; A1, B1; same pairs of Bs as pairs of As
3) A3, A1; A4, A7; A5, A6; A2, B2; same pairs of Bs as pairs of As
4) A4, A2; A5, A1; A6, A7; A3 B3; same pairs of Bs as pairs of As
5) A5, A3; A6, A2; A7, A1; A4, B4; same pairs of Bs as pairs of As
6) A6, A4; A7, A3; A1, A2; A5, B5; same pairs of Bs as pairs of As
7) A7, A5; A1, A4; A2, A3; A6, B6; same pairs of Bs as pairs of As
8) A1, B2; A2, B3; ...; A6, B6; A7, B1
9) A1, B3; A2, B4; ...; A5, B7; A6, B1; A7, B2
10) A1, B4; A2, B5; A3, B5; A4, B7; A5, B1; A6, B2; A7, B3
The days can be used in any order.
Victoria
