I would go to your Congressman's web page and see if he/her has a page for "constituent services" and look for the service academy section. They should list what they require. If it doesn't answer your question or provide a clear enough answer you should email the point of contact they list and ask that individual. For my Congressman they will take up to three and they will let me use two of them with people I have served with (squad leaders, commanders, etc.) and one has to be from a teacher, coach, etc. at my high school.
Every Congressman has different requirements so be sure to submit exactly what they need and no more! Attention to detail and all that! If you have any other questions about it you can shoot me a PM. Blessings!