Porter-Berger Link to Table Generator here. 5 9 4 8 10 1 6 2 7 3 Board 1 Board 2 Board 3 Board 4 Board 5 0

There are three conditions which could occur when letting someone into a round robin after the first round has been played.  In increasing order of complexity, they are

1. There are already an odd number of players in the tournament. By far the simplest case:  the new guy becomes the "Ghost" and plays a make-up game against the person who had a bye in the first round.

2. Adding two new players to a tournament. First, create a 1st round pairing in board number order of both the old and new (additional players) configurations. Insert a new board at the right end where the new players are assumed to have played their first round game (goes after the 8-3 board in this example).  Change pairings numbers as appropriate from board order listings.  These two 1st rounds from the 10 and 12 player event show the new players as 9 & 4.  Pairing numbers would change directly to the number shown on the 2nd line, e.g., 2 stays a 2, 5 becomes 6 and the original 9 becomes 11. The new players would have a make up game with each other and the tournament would last two rounds longer.
 1: 1-10 6-5 9-2 7-4 8-3 1: 1-12 7-6 11-2 8-5 10-3 9-4

3. Adding one player when there are an even number of players. As before, create 1st round pairings of both the current and next larger size tournament in board number order. This time the 1st round bye goes to the new guy and the original Board 1 becomes an ordinary board, shoving everything over to the right by one.  WARNING: In all PB tables, a player will have Black after having a bye or meeting the Ghost, not White.  To make the PB table work, choose reverse color assignments. Note the added space after the original round 1 to change the ghost board into an ordinary one.
 1: 1-10 6-5 9-2 7-4 8-3 1: 12-1 6-7 2-11 5-8 3-10 4-9

To create a board order diagram or chart of the 1st round, draw a horizontal rectangle and an appropriate number of vertical ones next to it.  Label the left of the horizontal (ghost) board with the maximum number of players and the right end of it with the 1st round opponent from the table (always 1).  Going counterclockwise, fill in the ghost's opponents in round number order until all rectangles are filled in on both ends. If done correctly for 10 players, your diagram will look like the one at the top of this page for Round 1.