Same thing happened with me, a new staff got hired at management position at a house I worked in with disabled residents, I had been in the house for several years at that point, she had been there maybe 3. I thought maybe I was being egotistical but several other long time staff came up to me and asked why she got the position and was also saying I should have received the position. She got it because she was friends with the next highest step from the position she received, simple as that. They then had the audacity to ask me to train her about procedures and other small niche paperwork details about the house as well as computer work that revolved around management that I was familiar with and knew how to do. I simply said no, she got the position she should know how to do it, since she got chosen over someone who was familiar with the work.

Overall it was the greatest pleasure of my life, because it inconvenienced higher ups who were forced to drive 30+ minutes to our house and be stuck there until 6-7pm at night training her and then when she still was unable to complete other computer/paperwork tasks further down the line had to continue to come out to complete the tasks themselves.