Reply All or Respond to last respondent in Salesforce Cases

Currently Fin will only respond to the person who opened the case. In many cases this as the case changes other people might be added to the case but Fin will only respond to the original individual who opened the case.  In some cases this person isn't any longer responsible for the case but is still the only one who Fin will respond to.

Fin should be able to reply all in the case or respond to the last respondent and not default back to the OG case opener.