Make a character in a font look like multiple characters of the same font

I have a free font in TTF and WOFF form. I want to create a ”multi-character”, by which I mean a character that when entered will be rendered as other (multiple) characters of that font. For example that when the user types 9 it is actually rendered how Stack Exchange is rendered in that font (yes the whole word). It’s not a monospace font.

Right now, I am using Font Creator from High-Logic and I’ve created a new glyph and am copying the individual glyphs to make a my multi-character. Besides character spacing (I will have to figure out what’s the right value for that), is there anything else I should take care of?