Changing the meeting abbreviations in the Legend is not possible using the plugin.
The meeting legend is stored in the BMLT server database. It is shared by everyone using that particular server. If a meeting abbreviation is changed it will affect every meeting on the server using that code.
With that said. IMHO. We should always be open to change. It might be easier to add a new code rather than change something that would affect 30+ areas using BMLT in the Florida and South Florida Region.