You're very wise to add GFCI protection to the circuits close to water where contact resistance is very low.
If you can locate the bedroom receptacle which feeds the bath fan & lights simply replace it with a GFCI receptacle and you should be fine.
I've discussed this with an AHJ,EE, CMP member friend and we do it all the time.
Good Luck from Columbiana, Alabama
Maurice Turgeon, http://thesemi-retiredelectrician.com