Les Règles

This player may move up to 3 squares (regardless of their MA), following all of the normal movement rules, when the opposing coach declares that one of their players is going to perform a Pass action.
This move is made after the range has been measured and the target square declared, but before the active player makes a Passing ability test. Making this move interrupts the activation of the opposition player performing the Pass action.
A player may use this skill when an opposition player uses the Dump-Off skill, but should this player Fall Over whilst moving, a Turnover is caused.
Additionally, during each Start of Drive sequence, after Step 2 but before Step 3, one Open player with this skill on the receiving team may move up to 3 squares (regardless of their MA). This skill may not be used if a touchback is caused when the kick deviates and does not allow the player to cross into their opponent's half of the pitch.

Q: Can multiple players from the same team use the On The Ball skill in response to the same Pass action? If so, what happens if one of them Falls Over before the others have been able to use the On The Ball skill? (p.79)
A: Yes. However, if one player Falls Over before the others have been able to use the On The Ball skill then the sequence ends and no further players can move.
Q: If multiple players on a team have the On the Ball skill, can they all move if an opposition player declares a Pass action? (p.79)
A: Yes if their controlling coach wishes.
Q: In Blood Bowl Sevens, can a player with the On the Ball skill use it to move into the area between both Lines of Scrimmage? (p.94)
A: Yes.
Q: Can the Dodge skill be used on moves outside of a player's activation, such as those provided from On the Ball, or the Blitz result on the Kick-off Event table? (p.75)
A: No. The Dodge skill can only be used to re-roll a Dodge roll during that player's activation during their own team turn.