Select Characters in the Insert menu to add glyphs with their character mappings and glyph names to the font. This option is available when the Font Overview window is active.
Select a Unicode block from the droplist, "Go to Unicode Block". Uncheck the "Sorted" field to sort the blocks in numerical code-point order instead of alphabetical order. if necessary, choose another installed font which includes the characters to be added. Characters can be added anyway, but it helps if the glyphs can be previewed.
Use the next and previous block or next and previous plane buttons to scroll through the font. The code point of the character to add can be found by entering the decimal value in the "Go to Code Point" field, or by entering the hexadecimal value preceded by a dollar sign. For example, enter 8364 or $20AC to find the Euro Sign (€). The Unicode name of the character can be used in the field, "Find Part of Character Name". For example, type "euro" to first find "EURO-CURRENCY SIGN," then "EURO SIGN" with Find Next.
Click on a character to select it and preview it in the glyph preview at bottom left. Double-click the character, or click the Add button, to add its code-point to the list of selected characters at the bottom of the dialog. Keep adding individual characters by double-clicking, or hold down the Shift key and double-click to add a range of characters. The codepoints will be displayed in Hexadecimal or Decimal notation depending on the setting in View -> Display. You can also type codepoints into the characters to add field, separated by commas (or hyphens to add a range of characters), or cut and paste a predefined list of characters from a text file. For example, pasting 256-383 then clicking OK would add the entire Latin Extended-A character set.
Click OK to dismiss the dialog and add the characters to the current font. If the glyphs exist in the overview sample font, and if "Show samples in empty glyphs" is on, grey outlines of the new characters will be displayed in the font overview.
Characters or entire character sets can also be added using Transform Scripts. See the topic: Glyph Transformer.
Note: The number of glyphs that may be included in one font is limited to 65535.