WE HAVE 12 PLAYERS -numbered 1 to 12- and they will always play IN FOUR GROUPS OF THREE [TRIPLETS]. Each series of MATCHES will involve all 4 triplets: playing in 2 simultaneous matches, i.e. 1,2,3 versus 4,5,6 AND 7,8,9 versus 10,11,12. After MATCH 1, the 4 triplets all change and MATCH 2 then takes place. Every Series of Matches - say up to 6 or if possible up to 12 - must involve all 12 players [the 4 triplets] playing at the same time, as above. What I am seeking is for a series of combinations for a total (unspecified, but at least 5) Series of Matches such that, at the end everyone will have played WITH and AGAINST every other player. With the minimum - or optimum- duplication. In theory, after 5 matches, every player should/could have played WITH 10 of the 11 opponents, and in the 6th game, they will be partnered by the 11th player and only doubles up with one player for a second game. At the same time - i.e. over 6 MATCHES - every player will play AGAINST the other players - AT BEST - with 4 opponents once and 7 opponents twice. And no one THREE TIMES! The first question is to determine if this is actually a possibility? Quite likely, the two conditions governing the choice of the triplets, means that the above 2 theories are impossible in practice. Therefore, what I'm really seeking is a Round Robin Scheduling for those 12 players in their triples, over an unspecified number of matches with the minimum of duplication. Thus far, using Trial-and-Error and complex 12x12 Grids, I have failed to complete 6 (or even 5) "perfect" combinations. Can anyone out there HELP ME please ?