hang on, tag on, supply, add, supplement, add on, affix, tack on, string up, depend, more...

remove, delete, erase

appendix, cervix, tongue, tonsils, clitoris, scrotum, testicles, prostate, more...

click, public, sure, reverse, sec, void, compare

adding on,   to add on,   add on to,   add onto,   to add onto,   to add on to,   add onto something,   add to the rest,   add to the end,   to tack on