Components can be add to a glyph with the Add Components sheet.
(contextual menu of the Editing Tool

typing will make the possible options smaller
arrow keys (up and down) will move up or down in the selection
tab jumps from 'Starts With' to 'Contains' and back 
enter add the component 
Copy Metrics will change the metrics of the glyph based on the added component 


Contextual Edit menu with component options