I do have a suggestion for your five rounds of play, but it may not be all that you had hoped for. First of all you need to identify a special player A, who will always play in the threesome. I have looked for other solutions with better balance between threesomes and foursomes but unfortunately I can't find any. So if you are happy with having the special player then the schedule below works nicely.
(A B C) (H F E K) (I D G J)
(A D E) (I J F B) (H K C G)
(A F G) (C H D J) (B E K I)
(A H I) (D B G K) (F C J E)
(A J K) (F H B D) (G I E C)
Player A, plays together with the other 10 players exactly once. All the other players play 4 rounds in foursomes and 1 round in a threesome, and will play with 6 of the other players (including A) exactly once, and play twice with the other 4 players.
Hope that helps.
