I'd like to clarify a little bit about the LOA. An LOA is a "Letter of ASSURANCE". The academy ASSURES (I.e. Guarantees) that you'll receive an appointment to the academy. Assuming a few conditions are met.
1. Application is 100% completed
2. You are 100% qualified. Academically, physically, and medically. This includes your CFA and medical evaluation.
3. You receive at least 1 nomination
Usually for air force, they don't give out an LOA unless your application is 100% complete already. There are some exceptions; usually for qualified athletes. But again; unlike the army and navy, the air force doesn't usually offer an LOA unless the application is 100% complete.
Now; to answer the OP's question. If your daughter's application is 100% complete. If she has passed her medical exam and is 100% qualified. She has passed her CFA. (I'm assuming YES to all of these because you said she was 3Q); and she HAS a Presidential Nomination; then the question is: "Can she receive an LOA". The answer is NO! I know..... Please explain.
As I said, an LOA is a "Conditional Appointment". Because your daughter has everything 100% complete, including a nomination, IF she was of the caliber for which the academy would offer her an LOA, they would simply offer her the "Appointment". There would be nothing to be "Conditional" about.
LOA's and Early Appointments. (Not to be confused with EA) are rare. They do give out some early appointments; (Obviously if it's before November, it's with a Non-Congressional Nomination because most congressional nominations haven't even been interviewed yet); these appointments are using a presidential, vp, rotc, etc... nomination. Others, who they really want too, but do have those types of nominations, would be the ones getting an LOA. So in your daughter's case, an LOA is not an option. There's nothing that's "Conditional". Everything is already in place. It's either an early appointment because she falls into the category where she walks on water and there's no way she can't receive an appointment...... or she waits along with everyone else. The walk on water applicant is usually the 4.0gpa; Ranked #1 in the class; ALL AP or IB classes/program; 32-36 ACT, 750+ SAT, hundreds of hours volunteering; plays multiple varsity sports; team captain; class officer; tons of other leadership experience; bla bla bla.
Now; if your daughter has this type of resume, then it's possible to get an early appointment. Again; an LOA is not an option. If she is more the average applicant (Average is an understatement because the Average cadet has a 3.86 gpa, 30 ACT, etc...) but if she isn't the "Walk on Water" applicant, she'll get notified of appointments like everyone else.
As for the academy SHIFTING around nominations, that is definitely something that they can do if they want to. I had a applicant who received an early appointment with a presidential nomination. But at the end of the season, the academy changed his nomination slot to one of our senator's slots. My son on the other hand, did it differently. He too received an early appointment in October with a Presidential nomination. We spoke with the senators and representative. Being it was an Early Appointment (Not an LOA), he was already accepted. Therefor, the senators and representative agreed with me that they SHOULDN'T interview my son or give him a nomination. This way the academy MUST USE the Presidential nomination that they gave him the appointment with. They can't change their mind and take away the appointment. This way, our state doesn't have to use up one of their slots on someone with an appointment already in hand.
Mind you, I'm talking about an APPOINTMENT in hand. Not an LOA or anything else. Normally, you want all the nominations you can get. But in our case, and the fact that our state is so small and doesn't get a lot of appointments, we wanted our state to get another appointment. So my son didn't interview or receive a congressional nomination. But again; he had his appointment in hand before November. So yes, if your daughter has multiple nominations, the academy can shift them around to their advantage.
Hope this helps explain some of the LOA and Early Appointment process. (Early Appointment is NOT the SAME as EA - early action eligible) Mike./...