It seems the simplest thing is to charge the fee only when it his charged by the investor. That eliminates the “why are you charging/retaining rate lock extension fees on some loans but not all” question. Where did you get your rate lock agreement (forms vendor, investor, in-house doc, etc.) and can you make changes to that wording “will” to “may”? As with any change, I recommend ensuring your forms vendor or investor allows for the change and if it is an in-house form having it reviewed by counsel.