umproper reentry

Question
Batter number 17 has just batted in the 3rd position for number 8.  After 8 bats and the inning is over the coach tells number 8 to go back in at second base.  The problem is he doesn't tell the umpire or the other coach of his move.  The opposing coach sees her reenter the game at second base.  During this next inning number 8 has a part in getting a base runner out who was attempting steal.
What is the proper call? Is 8 out of the game?  Is the base runner-stealer not out and given the base she was attempting to steal?  Help. Any other scenarios with this you have encountered?  Thanks!

Answer
Hi Steve,

In ASA, this is an unreported sub, when on defense and a US and MAKES A PLAY and is protested BEFORE the next pitch, or before the defense leaves the field (such as a 3rd out)

if they are a legal sub, such as your OP
1)the US is officially in the game,
2)the offensive manager has the option to take the result of the play.
3)OR have the last batter return to bat and assume the count and all runners return to the last base occupied prior to the play.

if protested AFTER the next pitch, the player is in the game and all play stands.

As you can see it depends on when you catch it.

NOW... I don't claim to be an expert in FED rules (you don't tell me the org) but I believe in FED play the 1st US is only a warning to the team, nothing more.

Mark