I assume that the initial setup has boardset 1 shared between tables 1 and 10, and table 11 is where E/W sit out (no boards). Boardsets 2 to 9 are on tables 2 to 9. If you insert an extra boardset between tables 5 and 6, on a relay (bystand) table, the movement becomes a 10 table share and relay (bystand) Mitchell. The downside is the the board numbers are no longer sequential between boardsets 5 and 7. You can truncate the movement after 9 rounds (all players play 27 boards) or complete it to allow all players to play 30 boards.