Occasionally I want to look up a word on Jisho.org from a device where it is inconvenient to use a Japanese keyboard. The default is to interpret an input as romaji if possible, so that's usually not a problem, but a word like 音{おん}韻{いん} would be romanized as onin, which Jisho parses as おにん, not おんいん, and does not find the word I am looking for.
When actually entering the text, I would enter o-n-n-i-n-n, but onnin, would be the romanization of おんにん. Is there a standard way to differentiate between んい and に in situations like this?