http://www.bahamas-travel.org/grand-bahamas-visitor/

Is a Visa required for a person who’s plane only stops temporarily in Nassau, Bahamas before next leg of trip?
The traveler is not a US or Canadian citizen and will travel on a Visitor Visa Issued by the British Consulate for travel from Indonesia to the Cayman Islands. The plane will stop for maybe 1 hour and then continue to Grand Cayman.
Thanks Folks! (she’s my fiance)
If she is not getting off the plane, then there is no problem.
If she is.. she will need to go thru bahamian immigration and onward.
Since the bahamas is a British Commonwealth, the British Consulate could add the bahamas to the Visitors Visa and she will not have a problem.
Nassau airport is not laid out well, and ALL deplaning visitors must pass thru immigration upon arrival.