new offer to the table, page-2

Just out of curiosity.

What would happen if i did not accept the offer by the 27th of september.
1) if it got up and accepted would my shares by default get lobbed into the $16 offer and just handed a check.
2) If I accepted, and there was a superior offer, would i be resigned to the offer i had already accepted from peabody an not entitled to the superior offer.

Sorry for my ignorance but have not been involved in this type of thing before.

Thanks for any advice