http://iscoresports.com/

Is it possible to insert a new play in the edit mode? For example, if I originally scored a batter as hitting a double but later wanted to make it a single with a subsequent advance to 2nd due to an error, is it possible to make that change in the edit mode?

Yes, you can make that specific edit. See the following link for information on post game editing:

http://iscoresports.com/baseball/kb/faq ... _edits.php

Want to echo , support .and Underline specific. That specific scenario can be done. But what can and what can not be edited post game is very specific. Some things can and some can't.