They can always be discouraged.

In fact one of the reported solutions offered in Camp David #2 was to blur the issue by accepting a quasi-recognition of the right of returns, yet implementing practical steps that will severely hamper "the right of refugees to return voluntarily to their homes"

Much the same as the infamous 242 of which every party offered their own biased interpretation, subject of course to the language of choice (English, French, Hebrew et. al.)