development corrupts

I'm curious. If the similarity between "in(-)add" and English isn't coincidence, is there a reason why you (and Afuna) use that construct instead of "add to/in"? (which is what I would expect to see in an English sentence, assuming the topic is adding someone to your flist.) Is it something that reflects syntax or morphology in ... er, whichever language this is embedded into (eg, "verb modifiers are prefixes, not suffixes" or some such)?</amateur language geek>