Serving as and Tack on

Tack on and serving as are semantically related. In some cases you can use "Tack on" instead a verb "Serving as".

Tack on verb - To join (something) to a mass, quantity, or number so as to bring about an overall increase.

Serving as and tack on are semantically related. Sometimes you can use "Serving as" instead a verb "Tack on".