If she's serious about moving, and can convince the recruitment companies of such, then they should be amenable to sending the cv around with the names of your sister, and maybe even her most recent company removed - a company description rather than a name.
However, recruitment companies are from past extensive experience (both working in one, and using their services) not worth getting involved with. The effort involved in using them is not worth the payoff.
If your sister is "known" in her working circles which you seem to imply if people would be bothered about passing on stories about her desire to move, then she must surely know enough people in the industry to be able to speak to people directly about possible job moves.
It's much much better to try to deal with companies direct rather than dealing with recruitment companies.