Be on a par and Tack on

Tack on and be on a par are semantically related. In some cases you can use "Tack on" instead a verb phrase "Be on a par".

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

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