I'm making changes to an existing project that uses fontello.
And I would like to add some icons to the project's font file.
What is the easiest way to to add those new icons? Can I create a 2nd font file in fontello and then somehow merge the two font files?
When you download a Fontello pack it includes a config.json file, which is a mapping of the characters included in your custom font. If you want to add more characters to your font, you should start by uploading this config file to fontello.com, change your selected characters and then download a new pack, making sure to replace all the fonts and css files (so that the new characters start working) and this config file (for next time you want to change the set of characters included).