Illegal re-entry

[Larks]

ASA Slow Pitch
Sitch...

Player X starts
Player Y enters to run.
Player X re-enters to field
Player Y enters again later to hit.
Player X re-enters again.

In A) X checked in and the umpire didnt catch the problem until after a pitch was delivered.

In B) A didnt check back in but did go to his/her defensive position. A pitch was delivered and the umpire was then made aware by the opposing team.

Penalty?