Hello mam521
I feel you, I went thru the same thing with one minor kid. I got very frustrated when I could not book any appointment online after trying with all USPS location even 50 miles from where we live.
The online appointment booking did not give me the option to schedule an appointment for 2 persons (my minor kid and me). This is my personal experience: I went to one USPS location to ask them if there is any possibility they can help. I was told to come back at a certain time window of a particular date of the week that they accept walk-in (for this location, it's Tuesday every week, from 10AM to 11AM). According to them, an application takes 15 minutes and there were only 2 staff in charge of passport application at the location I went (it also means they only accept 8 walk-in applications), so they advise me to come and get line ASAP because we would take 2 time slots. We did what I was told and submitted everything on 1/31 (still "In process" status). They did take my daughter (expired) green card, fyi.
Hope this helps and wish you the best of luck!
