Adding countries in a populated postgresql database

Hi, ive got a private osm server with data in a PostgreSQL database i have got a select few countries i have merged and then put into the PostgreSQL database. i connected my server to josm and have added a few rails ect ect. is there a way to add a new country into my PostgreSQL database along side the other countries already in there. currently i would have to merge the new countries with the already merged osm file. drop the database, recreate the database and then repopulate it, however this method would remove the changes i have added in from josm, Any help is always apprecieted :)