In the military justice system the major player is called the convening authority. The convening authority is a unit or organization commander who decides whether to refer a case to a court-martial, what type of court-martial, and then appoints the members of the court (i.e., the jury).
The convening authority is rarely a lawyer, although they are required to obtain the advice of a lawyer (the staff judge advocate) in certain cases, such as whether to convene a general court-martial. UCMJ Art. 34, 10 U.S.C. 834.
The convening authority has many of the powers conferred upon a district attorney in the civilian world. The convening authority has some powers that a district attorney does not have - such as picking the jury. A convening authority will normally pick mature and responsible officers for a court-martial, which usually means officers with long service and command experience.
All courts-martial start out with officer members, and ordinarily all members will be senior to the accused. An enlisted person such as your daughter has the right to request enlisted members, in which case the panel must have be at least 1/3 enlisted. UCMJ Art. 25(c), 10 U.S.C. 825(c). Your daughter appears to have so requested, and the convening authority appointed two enlisted members to serve. As with the officer members, the convening authority will usually pick enlisted members with long service and leadership experience. It is not unusual to have the court composed of senior officers and senior enlisted personnel.
Your daughter had the opportunity to examine (voir dire) the members to see if they had any prejudices, knowledge of the case, etc. She could challenge the members for cause, and had one preemptory challenge she could use to exclude a member for any reason. A general court-martial must have a least 5 members, and if the number was reduced to below 5 due to challenges, the convening authority would appoint replacement members.
The convening authority probably started with 5 officer members. When your daughter requested enlisted members the convening authority probably dismissed one officer member and appointed 2 enlisted members. One of the officer members was challenged off the panel leaving her with 3 officers and 2 enlisted members.
A military verdict usually requires a 2/3 majority. In your daughter's case that means 4 members had to agree to convict and so at least one enlisted member voted to convict her. Both the number of enlisted members and the number of votes required to convict are rounded up to whole persons: 1/3 of 5 equals 2; and 2/3 of 5 equals 4. (Note: A unanimous verdict is required in death penalty cases, and a majority vote for life imprisonment or confinement for more than 10 years. UCMJ Art. 52, 10 U.S.C. 852.)