I've been lurking around, reading up on the tons of information provided, but I'm actually a bit stuck now and unclear about something. Hope you could help!
Long story short, I've lived in the UK for almost 12 years now (I arrived with my family when I was 12) and like many EU nationals, my family never saw the need for spending money and applying for PR and eventual citizenship. Anyhow, I'm now interested in applying for citizenship and have been granted the indefinite leave to remain under the EU settled scheme, but I must now wait an year before applying for the citizenship and this is where the issue arises. I will be moving to the States for an year in the summer to do an internship as part of my degree, which means that I will have to wait another at least 9 months after I come back to apply for the citizenship (because I need to have been in the country for at least 9 months in the previous 12 before applying?).
I am thus considering applying for the EEU permanent residence certificate through a family member (my mum), based on her exercising treaty rights, and obviously applying for citizenship straight away. My question is - because I'm 23 years old now, would it be possible for me to submit a joint application with my mum so we could both get the EEU PR? I'm very confused as I read that the family member needs to be a dependent under the age of 21 and obviously don't want to keep delaying my citizenship application and have to wait almost another 2 years for it

Thanks in advance!
-Christian