That MAY be a VIP seat or it may just be that she was a relatively attractive female that they wanted to be on camera.
I have been to a couple Trump rallies. Bush and Romney prior to that. The campaign people will pick good looking people to sit behind the candidate. They will be on camera in the background. Especially IF you are a woman of color. Or a man of color. Which tend to be in the minority at Trump rallies.
I have never been picked. However, my son and his buddy were last year in Manchester, NH. They were both 25 year old young men wearing sport coats.
Wow, to sit behind Trump at a rally would be an experience.
Did they scan/copy your son’s ID ?
In other words, would there have been a record of who was sitting behind the President ? .